<HTML> <HEAD>
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<BODY>
<H1><IMG SRC="examples/dna.small.gif" ALT="[logo]">
CGI.pm - a Perl5 CGI Library</H1>
Version 2.36, 5/10/97, L. Stein
<p>
      
<strong>WARNING:</strong> The overloaded double-quote ("") operator
has been removed.  In previous versions, CGI objects were
automatically interpolated as HTML into double-quoted strings.  This
was useful for debugging, but broke in newer versions of Perl.

<H2>Abstract</H2> This perl 5 library uses objects to create Web
fill-out forms on the fly and to parse their contents.  It provides a
simple interface for parsing and interpreting query strings passed to
CGI scripts.  However, it also offers a rich set of functions for
creating fill-out forms. Instead of remembering the syntax for HTML
form elements, you just make a series of perl function calls. An
important fringe benefit of this is that the value of the previous
query is used to initialize the form, so that the state of the form is
preserved from invocation to invocation.

<P>Everything is done through a ``CGI'' object.  When you create one
of these objects it examines the environment for a query string,
parses it, and stores the results. You can then ask the CGI object to
return or modify the query values.  CGI objects handle POST and GET
methods correctly, and correctly distinguish between scripts called
from &lt;ISINDEX&gt; documents and form-based documents. In fact you
can debug your script from the command line without worrying about
setting up environment variables.

<P>A script to create a fill-out form that remembers its state each
time it's invoked is very easy to write with CGI.pm:

<PRE>
#!/usr/local/bin/perl

use CGI qw(:standard);

print header;
print start_html('A Simple Example'),
    h1('A Simple Example'),
    start_form,
    "What's your name? ",textfield('name'),
    p,
    "What's the combination?",
    p,
    checkbox_group(-name=&gt;'words',
		   -values=&gt;['eenie','meenie','minie','moe'],
		   -defaults=&gt;['eenie','minie']),
    p,
    "What's your favorite color? ",
    popup_menu(-name=&gt;'color',
	       -values=&gt;['red','green','blue','chartreuse']),
    p,
    submit,
    end_form,
    hr;

if (param()) {
    print 
	"Your name is",em(param('name')),
	p,
	"The keywords are: ",em(join(", ",param('words'))),
	p,
	"Your favorite color is ",em(param('color')),
	hr;
}
print a({href=&gt;'../cgi_docs.html'},'Go to the documentation');
</PRE>

<A HREF="examples/tryit.cgi">Select this link to try the script</A>
<BR><A HREF="examples/">More scripting examples</A>

<p>

<A NAME="contents">
<H2>Contents</H2>
</A>
<MENU>
  <LI><A HREF="#installation">Downloading & Installation</A>
  <LI><A HREF="#query">Creating a new CGI query object</A>
  <LI><A HREF="#saving">Saving the state of the form</A>
  <LI><A HREF="#named_param">CGI Functions that Take Multiple Arguments</A>
  <LI><A HREF="#header">Creating the HTTP header</A>
  <LI><A HREF="#html">HTML shortcuts</A>
  <LI><A HREF="#forms">Creating forms</A>
  <LI><A HREF="#import">Importing CGI methods</A>
  <LI><A HREF="#debugging">Debugging</A>
  <LI><A HREF="#environment">HTTP session variables</A>
  <LI><A HREF="#cookies">Netscape Cookies</A>
  <li><a href="#frames">Support for Netscape frames</a>
  <li><a href="#javascripting">Support for JavaScript</a>
  <li><a href="#stylesheets">Limited Support for Cascading Style Sheets</a>
  <LI><A HREF="#nph">Using NPH Scripts</A>
  <LI><A HREF="#advanced">Advanced techniques</A>
  <LI><A HREF="#mod_perl">Using CGI.pm with mod_perl and FastCGI</A>
  <LI><A HREF="#migrating">Migrating from cgi-lib.pl</A>
  <LI><a href="#upload_caveats">Using the File Upload Feature</a>
  <LI><A HREF="#non_unix">Using CGI.pm on non-Unix Platforms</A>
  <LI><A HREF="#future">The Relationship of CGI.pm to the CGI::* Modules</A>
  <LI><A HREF="#distribution">Distribution information</A>
  <LI><A HREF="#mailingList">CGI-perl mailing list</A>
  <LI><A HREF="#new">What's new in version 2.36?</A>
</MENU>

<HR>
<A NAME="installation">
<H2>Downloading & Installation</H2>
</A>
<ul>
  <li><STRONG><A HREF="CGI.pm.tar.gz">Download full package (gzip tar archive)</A></STRONG>
  <li><STRONG><A HREF="CGIpm.zip">Download full package (pkzip archive)</A></STRONG>
  <li><STRONG><A HREF="CGI.pm.sit.hqx">Download full package (Macintosh stuffit archive)</A></STRONG>
  <li><strong><A HREF="CGI.pm">Download just the CGI module (uncompressed)</a></strong>
</ul>

<P>This package requires perl 5.001m or higher.  (Perl 5.003 is
<strong>highly</strong> recommended because of a security hole in
earlier versions of perl.)  To use CGI.pm
simply install it in your perl library directory.  On most systems
this will be <CODE>/usr/local/lib/perl5</CODE>, but check with the
administrator of your system to be sure.  If you know the location of
the directory, you can move the module directly: <pre>
    cp CGI.pm /usr/local/lib/perl5/
</pre>
(This assumes that the perl library is located at <code>/usr/local/lib/perl5</code>.
Windows users should of course use the "copy" command rather than "cp").
<P>
In most cases, though, you should have perl do the installation
for you.  Move to the directory containing CGI.pm and type the
following commands:
<PRE>
   % perl Makefile.PL
   % make
   % make install
</PRE>
You may need to be root to do the last step.
<p>
This will create two new files in your Perl library.  <b>CGI.pm</b> is the
main library file.  <b>Carp.pm</b> (in the subdirectory "CGI") contains
some optional utility
routines for writing nicely formatted error messages into your
server logs.  See the Carp.pm man page for more details.
<p>
<strong>If you get error messages when you try to install</strong>,
then you are either:
<ol>
  <li> Running a Windows NT port of Perl (or another port) that
      doesn't have the current MakeMaker program built into it.
  <li> Have an old version of perl.  In particular, version 5.000
      will complain that (nonexistent) .c and .o files are missing.  
</ol>
In either of these cases, don't panic.
Just do a direct copy as shown above.  To install the CGI::Carp
routines, you'll need to create a subdirectory called "CGI"
in your perl library directory and copy ./CGI/Carp.pm into it.
<p>

<STRONG>If you do not have sufficient privileges to install into
/usr/local/lib/perl5</STRONG>, you can still use CGI.pm.  Place it
in some convenient place, for example, in
<CODE>/usr/local/etc/httpd/cgi-bin</CODE> and preface your CGI
scripts with a preamble something like the following:

<blockquote><pre>
use lib '/usr/local/etc/httpd/cgi-bin';
use CGI;
</pre></blockquote>

Users of pre-5.002 versions of perl (which includes NT perl) will have
to use this form instead:
<blockquote>
<PRE>
BEGIN {
     unshift(@INC,'/usr/local/etc/httpd/cgi-bin');
}
use CGI;
</PRE>
</blockquote>

Be sure to replace /usr/local/etc/httpd/cgi-bin with the true
location of CGI.pm.

<P>
<A HREF="#non_unix">Notes on using CGI.pm in NT and other non-Unix platforms</A>
<hr>

<A NAME="query">
<H2>Creating a new CGI object</H2>
</A>
The most basic use of CGI.pm is to get at the query parameters
submitted to your script.  To create a new CGI object that 
contains the parameters passed to your script, put the following
at the top of your perl CGI programs:

<PRE>
    use CGI;
    $query = new CGI;
</PRE>

In the object-oriented world of Perl 5, this code calls the new()
method of the CGI class and stores a new CGI object into the variable
named $query.  The new() method does all the dirty work of parsing
the script parameters and environment variables and stores its results
in the new object.  You'll now make method calls with this object to
get at the parameters, generate form elements, and do other useful things.
<P>
An alternative form of the new() method allows you to read
script parameters from a previously-opened file handle:
<PRE>
    $query = new CGI(FILEHANDLE)
</PRE>

The filehandle can contain a URL-encoded query string, or can be a
series of newline delimited TAG=VALUE pairs.  This is compatible with
the save() method.  This lets you save the state of a CGI script to a
file and reload it later.  It's also possible to save the contents of
several query objects to the same file, either within a single script
or over a period of time.  You can then reload the multiple records
into an array of query objects with something like this:

<blockquote><pre>
open (IN,"test.out") || die;
while (!eof(IN)) {
    my $q = new CGI(IN);
    push(@queries,$q);
}
</pre></blockquote>

You can make simple databases this way, or create a guestbook.  If
you're a Perl purist, you can pass a reference to the filehandle glob
instead of the filehandle name.  This is the "official" way to pass
filehandles in Perl5:

<blockquote><pre>
    my $q = new CGI(\*IN);
</pre></blockquote>

(If you don't know what I'm talking about, then you're not a Perl
purist and you needn't worry about it.)

<p>

You can initialize a CGI object from an associative-array reference.
Values can be either single- or multivalued:

<blockquote><pre>
$query = new CGI({'dinosaur'=&gt;'barney',
                  'song'=&gt;'I love you',
                  'friends'=&gt;[qw/Jessica George Nancy/]});
</pre></blockquote>

Finally, you can initialize a CGI object by passing a URL-style query
string to the new() method like this:

<blockquote><pre>
$query = new CGI('dinosaur=barney&amp;color=purple');
</pre></blockquote>

This form also allows you to create a CGI object that is initially empty:

<blockquote><pre>
$empty_query = new CGI('');
</pre></blockquote>

See <A HREF="#advanced">advanced techniques</A> for more information.

<A NAME="keywords">
<H3>Fetching A List Of Keywords From The Query</H3>
</A>
<PRE>
    @keywords = $query-&gt;keywords
</PRE>
If the script was invoked as the result of an &lt;ISINDEX&gt; search, the
parsed keywords can be obtained with the keywords() method.  This method
will return the keywords as a perl array.

<A NAME="parameters">
<H3>Fetching The Names Of All The Parameters Passed To Your
Script</H3>
</A>
<PRE>
    @names = $query-&gt;param
</PRE>
If the script was invoked with a parameter list
(e.g. "name1=value1&amp;name2=value2&amp;name3=value3"), the param()
method will return the parameter names as a list.  For backwards
compatability, this method will work even if the
script was invoked as an &lt;ISINDEX&gt; script: in this case there
will be a single parameter name returned named 'keywords'.

<A NAME="values"><H3>Fetching The Value(s) Of A Named Parameter</H3>
</A>
<PRE>
   @values = $query-&gt;param('foo');
             -or-
   $value = $query-&gt;param('foo');
</PRE>
Pass the param() method a single argument to fetch the value of the
named parameter. If the parameter is multivalued (e.g. from multiple
selections in a scrolling list), you can ask to receive an array.  Otherwise
the method will return a single value.
<P>
As of version 1.50 of this library, the array of parameter names returned
will be in the same order in which the browser sent them.  Although
this is not guaranteed to be identical to the order in which the
parameters were defined in the fill-out form, this is usually the
case.

<A NAME="setting">
<H3>Setting The Value(s) Of A Named Parameter</H3>
</A>
<PRE>
   $query-&gt;param('foo','an','array','of','values');
                   -or-
   $query-&gt;param(-name=&gt;'foo',-values=&gt;['an','array','of','values']);
</PRE>
This sets the value for the named parameter 'foo' to one or more
values.  These values will be used to initialize form elements, if
you so desire.  Note that this is the one way to forcibly change the value
of a form field after it has previously been set.
<p>
The second example shows an alternative "named parameter" style of function
call that is accepted by most of the CGI methods.  See <a href="#named_param">
Calling CGI functions that Take Multiple Arguments</a> for an explanation of
this style.

<A NAME="append">
<H3>Appending a Parameter</H3>
</A>
<PRE>
   $query-&gt;append(-name=&gt;'foo',-values=&gt;['yet','more','values']);
</PRE>
This adds a value or list of values to the named parameter.  The
values are appended to the end of the parameter if it already exists.
Otherwise the parameter is created.

<A NAME="deleting">
<H3>Deleting a Named Parameter Entirely</H3>
</A>
<PRE>
   $query-&gt;delete('foo');
</PRE>
This deletes a named parameter entirely.  This is useful when you
want to reset the value of the parameter so that it isn't passed
down between invocations of the script.

<A NAME="deleting_all">
<H3>Deleting all Parameters</H3>
</A>
<PRE>
   $query-&gt;delete_all();
</PRE>
This deletes all the parameters and leaves you with an empty CGI
object.  This may be useful to restore all the defaults produced by
the form element generating methods.

<A NAME="importing">
<H3>Importing parameters into a namespace</H3>
</A>
<PRE>
   $query-&gt;import_names('R');
   print "Your name is $R::name\n"
   print "Your favorite colors are @R::colors\n";
</PRE>
This imports all parameters into the given name space.  For example,
if there were parameters named 'foo1', 'foo2' and 'foo3', after
executing <CODE>$query-&gt;import_names('R')</CODE>, the variables
<CODE>@R::foo1, $R::foo1, @R::foo2, $R::foo2,</CODE> etc. would
conveniently spring into existence.  Since CGI has no way of
knowing whether you expect a multi- or single-valued parameter,
it creates two variables for each parameter.  One is an array,
and contains all the values, and the other is a scalar containing
the first member of the array.  Use whichever one is appropriate.
For keyword (a+b+c+d) lists, the variable @R::keywords will be
created.
<P>
If you don't specify a name space, this method assumes namespace "Q".

<P><STRONG>Warning</STRONG>: do not import into namespace 'main'.  This
represents a major security risk, as evil people could then use this
feature to redefine central variables such as @INC.
CGI.pm will exit with an error if you try to do this.
<P>
<EM>Note</EM>: this method used to be called import().  As of
version 2.20 <code>import()</code> has been changed to be consistent
with other Perl modules.  Please change all occurrences of import() to
import_names().
<P>
<A HREF="#contents">Table of contents</A>

<HR>
<A NAME="saving">
<H2>Saving the Current State of a Form</H2>

<H3>Saving the State to a File</H3>
</A>
<PRE>
   $query-&gt;save(FILEHANDLE)
</PRE>
This writes the current query out to the file handle of your choice.
The file handle must already be open and be writable, but other than
that it can point to a file, a socket, a pipe, or whatever.  The contents
of the form are written out as TAG=VALUE pairs, which can be reloaded
with the new() method at some later time.  You can write out multiple
queries to the same file and later read them into query objects one by one.

<p>
See <A HREF="#advanced"> advanced techniques</A> for more information.

<H3><A NAME="self_referencing">
Saving the State in a Self-Referencing URL</A></H3>
<PRE>
   $my_url=$query-&gt;self_url
</PRE>
This call returns a URL that, when selected, reinvokes this script with
all its state information intact.  This is most useful when you want to
jump around within a script-generated document using internal anchors, but
don't want to disrupt the current contents of the form(s).  See <A HREF="#advanced">
advanced techniques</A> for an example.
<P>
If you'd like to get the URL without the entire query string appended to
it, use the <code>url()</code> method:
<PRE>
   $my_self=$query-&gt;url
</PRE>

<A HREF="#contents">Table of contents</A>

<HR>
<H3><A NAME="named_param">
    Calling CGI Functions that Take Multiple Arguments</A>
</H3>

In versions of CGI.pm prior to 2.0, it could get difficult to remember
the proper order of arguments in CGI function calls that accepted five
or six different arguments.  As of 2.0, there's a better way to pass
arguments to the various CGI functions.  In this style, you pass a
series of name=&gt;argument pairs, like this:

<PRE>
   $field = $query-&gt;radio_group(-name=&gt;'OS',
                                -values=&gt;[Unix,Windows,Macintosh],
                                -default=&gt;'Unix');
</PRE>
The advantages of this style are that you don't have to remember the
exact order of the arguments, and if you leave out a parameter, iit
will usually default to some reasonable value.  If you provide
a parameter that the method doesn't recognize, it will usually do
something useful with it, such as incorporating it into the HTML
tag as an attribute.  For example if Netscape decides next week to add a new
JUSTIFICATION parameter to the text field tags, you can start using
the feature without waiting for a new version of CGI.pm:

<PRE>
   $field = $query-&gt;textfield(-name=&gt;'State',
                              -default=&gt;'gaseous',
                              -justification=&gt;'RIGHT');
</PRE>

This will result in an HTML tag that looks like this:

<PRE>
   &lt;INPUT TYPE="textfield" NAME="State" VALUE="gaseous"
          JUSTIFICATION="RIGHT"&gt;
</PRE>

Parameter names are case insensitive: you can use -name, or -Name or
-NAME.  You don't have to use the hyphen if you don't want to.  After
creating a CGI object, call the <STRONG><CODE>
use_named_parameters()</CODE></STRONG> method with
a nonzero value.  This will tell CGI.pm that you intend to use named
parameters exclusively:

<PRE>
   $query = new CGI;
   $query-&gt;use_named_parameters(1);
   $field = $query-&gt;radio_group('name'=&gt;'OS',
                                'values'=&gt;['Unix','Windows','Macintosh'],
                                'default'=&gt;'Unix');
</PRE>

Actually, CGI.pm only looks for a hyphen in the first parameter.  So
you can leave it off subsequent parameters if you like.  Something to
be wary of is the potential that a string constant like "values" will
collide with a keyword (and in fact it does!) While Perl usually
figures out when you're referring to a function and when you're
referring to a string, you probably should put quotation marks around
all string constants just to play it safe.
<P>
<A HREF="#contents">Table of contents</A>

<HR>
<H2><A NAME="header">
Creating the HTTP Header</A>
</H2>

<H3><A NAME="standard_header">
Creating the Standard Header for a Virtual Document</A>
</H3>
<PRE>
   print $query-&gt;header('image/gif');
</PRE>
This prints out the required HTTP Content-type: header and the requisite
blank line beneath it.  If no parameter is specified, it will default to
'text/html'.
<P>
An extended form of this method allows you to specify a status code
and a message to pass back to the browser:
<PRE>
   print $query-&gt;header(-type=&gt;'image/gif',
                        -status=&gt;'204 No Response');
</PRE>

This presents the browser with a status code of 204 (No response).
Properly-behaved browsers will take no action, simply remaining on the
current page.  (This is appropriate for a script that does some
processing but doesn't need to display any results, or for a script
called when a user clicks on an empty part of a clickable image map.)

<P>

Several other named parameters are recognized.  Here's a
contrived example that uses them all:

<PRE>
   print $query-&gt;header(-type=&gt;'image/gif',
                        -status=&gt;'402 Payment Required',
                        -expires=&gt;'+3d',
                        -cookie=&gt;$my_cookie,
                        -Cost=&gt;'$0.02');
</PRE>

<h4>-expires</h4>

Some browsers, such as Internet Explorer, cache the output of CGI
scripts.  Others, such as Netscape Navigator do not.  This leads to
annoying and inconsistent behavior when going from one browser to
another.  You can force the behavior to be consistent by using the
<strong>-expires</strong> parameter.  When you specify an absolute or
relative expiration interval with this parameter, browsers and
proxy servers will cache the script's output until the indicated
expiration date.  The following forms are all valid for the
<strong>-expires</strong> field: <pre>
	+30s                              30 seconds from now
	+10m                              ten minutes from now
	+1h	                          one hour from now
        -1d                               yesterday (i.e. "ASAP!")
	now                               immediately
	+3M                               in three months
        +10y                              in ten years time
	Thursday, 25-Apr-96 00:40:33 GMT  at the indicated time & date
</pre>

When you use <strong>-expires</strong>, the script also generates a
correct time stamp for the generated document to ensure that your
clock and the browser's clock agree.  This allows you to create
documents that are reliably cached for short periods of time.

<p>

<strong>CGI::expires()</strong> is the static function call used internally that turns
relative time intervals into HTTP dates.  You can call it directly if
you wish.

<h4>-cookie</h4>

The <strong>-cookie</strong> parameter generates a header that tells
Netscape browsers to return a "magic cookie" during all subsequent
transactions with your script.  Netscape cookies have a special format
that includes interesting attributes such as expiration time.  Use the
<a href="#cookies">cookie()</a> method to create and retrieve session
cookies.  The value of this parameter can be either a scalar value or
an array reference.  You can use the latter to generate multiple
cookies.  (You can use the alias <strong>-cookies</strong> for
readability.)


<h4>-nph</h4>

The <strong>-nph</strong> parameter, if set to a non-zero value, will
generate a valid header for use in no-parsed-header scripts.  For
example:

<blockquote><pre>
print $query-&gt;header(-nph=&gt;1,
                        -status=&gt;'200 OK',
                        -type=&gt;'text/html');
</pre></blockquote>

You will need to use this if:

<ol>
  <li>You are using Microsoft Internet Information Server.
  <li>If you need to create unbuffered output, for example for use
      in a "server push" script.
  <li>To take advantage of HTTP extensions not supported by your server.
</ol>

See <a href="#nph">Using NPH Scripts</a> for more information.

<h4>Other header fields</h4>

Any other parameters that you pass to <strong>header()</strong> will be turned
into correctly formatted HTTP header fields, even if they aren't called for
in the current HTTP spec.  For example, the example that appears a few paragraphs
above creates a field that looks like this:
<pre>
   Cost: $0.02
</pre>

You can use this to take advantage of new HTTP header fields without
waiting for the next release of CGI.pm.

<A NAME="redirect">
<H3>Creating the Header for a Redirection Request</H3>
</A>
<PRE>
   print $query-&gt;redirect('http://somewhere.else/in/the/world');
</PRE>
This generates a redirection request for the remote browser.  It will
immediately go to the indicated URL.  You should exit soon after this.
Nothing else will be displayed.
<P>
You can add your own headers to this as in the header() method.
<P>
You should always use absolute or full URLs in
redirection requests.  Relative URLs will <strong>not</strong> work
correctly.

<p>

An alternative syntax for <code>redirect()</code> is:

<blockquote><pre>
print $query-&gt;redirect(-uri=&gt;'http://somewhere.else/',
                          -nph=&gt;1);
</pre></blockquote>

The <strong>-nph</strong> parameter, if non-zero tells CGI.pm that
this script is running as a no-parsed-header script.  See <a
href="#nph">Using NPH Scripts</a> for more information.

<A HREF="#contents">Table of contents</A>

<HR>
<A NAME="html">
<H2>HTML Shortcuts</H2>
</A>

<H3>Creating an HTML Header</H3>
<PRE>
   <EM>named parameter style</EM>
   print $query-&gt;start_html(-title=&gt;'Secrets of the Pyramids',
                            -author=&gt;'fred@capricorn.org',
                            -base=&gt;'true',
			    -meta=&gt;{'keywords'=&gt;'pharoah secret mummy',
                                    'copyright'=&gt;'copyright 1996 King Tut'},
			    -style=>{'src'=>'/styles/style1.css'},
                            -BGCOLOR=&gt;'blue');

   <EM>old style</EM>
   print $query-&gt;start_html('Secrets of the Pyramids',
                            'fred@capricorn.org','true');
</PRE>
This will return a canned HTML header and the opening &lt;BODY&gt; tag.  
All parameters are optional:
<UL>
  <LI>The title (<strong>-title</strong>)
  <LI>The author's e-mail address (will create a &lt;LINK REV="MADE"&gt; tag if present
      (<strong>-author</strong>)
  <LI>A true flag if you want to include a &lt;BASE&gt; tag in the header
      (<strong>-base</strong>). This
       helps resolve relative addresses to absolute ones when the document is moved, 
       but makes the document hierarchy non-portable.  Use with care!
  <LI>A <strong>-xbase</strong> parameter, if you want to include a &lt;BASE&gt; tag that points
      to some external location.  Example:
      <pre>
      print $query-&gt;start_html(-title=&gt;'Secrets of the Pyramids',
                               -xbase=&gt;'http://www.nile.eg/pyramid.html');
      </pre>
  <LI>A <strong>-target</strong> parameter, if you want to have all links and fill
      out forms on the page go to a different frame.  Example:
      <pre>
      print $query-&gt;start_html(-title=&gt;'Secrets of the Pyramids',
                               -target=&gt;'answer_frame');
      </pre>
      <strong>-target</strong> can be used with either
      <strong>-xbase</strong> or <strong>-base</strong>.
  <LI>A <strong>-meta</strong> parameter to define one or more &lt;META&gt; tags.  Pass
      this parameter a reference to an associative array containing key/value pairs.  Each
      pair becomes a &lt;META&gt; tag in a format similar to this one.
      <blockquote><pre>
      &lt;META NAME="keywords" CONTENT="pharoah secret mummy"&gt;
      &lt;META NAME="description" CONTENT="copyright 1996 King Tut"&gt;
      </pre></blockquote>
      There is no support for the HTTP-EQUIV type of &lt;META&gt; tag.  This is
      because you can modify the HTTP header directly with the
      <a href="#header">header</a> method.  Example:
      <blockquote>
      <pre>
      print $q-&gt;header(-Refresh=>'10; URL=http://www.capricorn.com');
      </pre>
      </blockquote>
  <li>A <strong>-style</strong> parameter to define a cascading stylesheet.
      More information on this can be found in <a
      href="#stylesheets">Limited Support for Cascading Style Sheets</a>
  <li>A <strong>-head</strong> parameter to define other arbitrary elements
      of the &lt;HEAD&gt; section.  For example:
      <pre>
      print $q-&gt;header(-head=&gt;link({-rel=&gt;'next',
                       -href=&gt;'http://www.capricorn.com/s2.html'}));

      </pre>
      or even
      <pre>
      print $q-&gt;header(-head=&gt;[ link({-rel=&gt;'next',
				      -href=&gt;'http://www.capricorn.com/s2.html'}),
			        link({-rel=&gt;'previous',
				      -href=&gt;'http://www.capricorn.com/s1.html'})
			      ]
		      );
      </pre>
  <LI>A <strong>-script</strong> parameter to define Netscape <a
      href="#javascripting">JavaScript</a> functions
      to incorporate into the HTML page.  This is the preferred way to
      define a library of JavaScript functions that will be called
      from elsewhere within the page.  CGI.pm will attempt to format
      the JavaScript code in such a way that non-Netscape browsers won't
      try to display the JavaScript
      code.  Unfortunately some browsers get confused nevertheless.
      Here's an example of how to create a JavaScript library and
      incorporating it into the HTML code header:
      <pre>
      $query = new CGI;
      print $query-&gt;header;
      
      $JSCRIPT=&lt;&lt;END;
      // Ask a silly question
      function riddle_me_this() {
         var r = prompt("What walks on four legs in the morning, " +
                       "two legs in the afternoon, " +
                       "and three legs in the evening?");
         response(r);
      }
      // Get a silly answer
      function response(answer) {
         if (answer == "man")
            alert("Right you are!");
         else
            alert("Wrong!  Guess again.");
      }
      END
      
      print $query-&gt;start_html(-title=&gt;'The Riddle of the Sphinx',
                               -script=&gt;$JSCRIPT);
      </pre>

      Netscape 3.0 allows you to place the JavaScript code in an external
      document and refer to it by URL.  This allows you to keep the JavaScript
      code in a file or CGI script rather than cluttering up each page with the
      source.  Netscape 3.0 and Internet Explorer also recognize a "language"
      parameter that allows you to use other languages, such as VBScript and
      PerlScript (yes indeed!)  To use these attributes pass a HASH
      reference in the <strong>-script</strong> parameter containing one
      or more of the keys <strong>language</strong>, <strong>src</strong>, or
      <strong>code</strong>.  Here's how to refer to an external script URL:

      <pre>
      print $q-&gt;start_html(-title=&gt;'The Riddle of the Sphinx',
			   -script=>{-language=&gt;'JavaScript',
                                   -src=>'/javascript/sphinx.js'}
                              );
     </pre>

     Here's how to refer to scripting code incorporated directly into the page:

     <pre>

     print $q-&gt;start_html(-title=&gt;'The Riddle of the Sphinx',
                          -script=&gt;{-language=&gt;'PerlScript',
                                    -code-&gt;'print "hello world!\n;"'
                             );
     </pre>

  <LI>A <strong>-noScript</strong> parameter to pass some HTML that will be displayed
      in browsers that do not have JavaScript (or have JavaScript turned off).
  <LI><strong>-onLoad</strong> and <strong>-onUnload</strong> parameters to
      register JavaScript event handlers to be executed when the
      page generated by your script is opened and closed respectively.
      Example:
      <pre>
      print $query-&gt;start_html(-title=&gt;'The Riddle of the Sphinx',
                                  -script=&gt;$JSCRIPT,
                                  -onLoad=&gt;'riddle_me_this()');
      </pre>
      See <a href="#javascripting">JavaScripting</a> for more details.
  <LI>Any additional attributes you want to incorporate into the &lt;BODY&gt;
       tag (as many as you like).  This is a good way to incorporate other
      Netscape extensions, such as background color and wallpaper pattern.
      (The example above sets the page background to a vibrant blue.)  You can
      use this feature to take advantage of new HTML features without
      waiting for a CGI.pm release.
</UL>

<H3>Ending an HTML Document</H3>
<PRE>
  print $query-&gt;end_html
</PRE>
This ends an HTML document by printing the &lt;/BODY&gt; &lt;/HTML&gt; tags.

<H3>Other HTML Tags</H3>

CGI.pm provides shortcut methods for many other HTML tags.  All HTML2
tags and the Netscape extensions are supported, as well as the
HTML3 tags that are in common usage (including tables).  Unpaired
tags, paired tags, and tags that contain attributes are all supported
using a simple syntax.

<h4>Unpaired Tags</h4>

Unpaired tags include &lt;P&gt;, &lt;HR&gt; and &lt;BR&gt;.  The
syntax for creating them is:

<pre>
   print $query-&gt;hr;
</pre>

This prints out the text "&lt;hr&gt;".

<h4>Paired Tags</h4>

Paired tags include &lt;EM&gt;, &lt;I&gt; and the like.  The syntax
for creating them is:

<pre>
   print $query-&gt;em("What a silly art exhibit!");
</pre>

This prints out the text "&lt;em&gt;What a silly art
exhibit!&lt;/em&gt;".

<p>

You can pass as many text arguments as you like: they'll be
concatenated together with spaces.  This allows you to create nested
tags easily:

<pre>
   print $query-&gt;h3("The",$query-&gt;em("silly"),"art exhibit");
</pre>

This creates the text:
<pre>
   &lt;h3&gt;The &lt;em&gt;silly&lt;/em&gt; art exhibit&lt;/h3&gt;
</pre>

<p>

When used in conjunction with the <a href="#import">import</a>
facility, the HTML shortcuts can make CGI scripts easier to read.  For
example:

<pre>
   use CGI ':standard';
   print h1("Road Guide"),
         ol(
          li(a {href=&gt;"start.html"},"The beginning"),
          li(a {href=&gt;"middle.html"},"The middle"),
          li(a {href=&gt;"end.html"},"The end")
         );
</pre>

<p>

Most HTML tags are represented as lowercase function calls.  There are
a few exceptions:

<ol>
  <li>The &lt;tr&gt; tag used to start a new table row conflicts with the
      perl <cite>translate</cite> function <code>tr()</code>.  Use
      TR() or Tr() instead.
  <li>The &lt;param&gt; tag used to pass parameters to an applet
      conflicts with CGI's own <code>param() </code> method.  Use
      PARAM() instead.
  <li>The &lt;select&gt; tag used to create selection lists conflicts
      with perl's select() function.  Use <code>Select()</code> instead.
</ol>

<h4>Tags with Attributes</h4>

To add attributes to an HTML tag, simply pass a reference to an
associative array as the first argument.  The keys and values of the
associative array become the names and values of the attributes.  You
can use an initial hyphen (<cite>-name</cite>) for readability if you
wish:

<pre>
   use CGI shortcuts;
   print a({href=&gt;"bad_art.html"},"Jump to the silly exhibit");
</pre>

<P>
<A HREF="#contents">Table of contents</A>

<HR>

<A NAME="forms">
<H2>Creating Forms</H2>
</A>
<EM>General note 1.</EM>
The various form-creating methods all return
strings to the caller.  These strings will contain the HTML code
that will create the requested form element.  You are responsible for
actually printing out these strings.  It's set up this way so that you
can place formatting tags around the form elements.
<P>
<A NAME="overriding">
<EM>General note 2.</EM>
</A>
The default values that you specify for the
forms are only used the <STRONG>first</STRONG> time the script is invoked.  If there
are already values present in the query string, they are used, even if
blank.

<P>If you want to change the value of a field from its previous
value, you have two choices:

<OL>
  <LI> call the <STRONG>param()</STRONG> method to set it.
  <LI> use the <B>-override</B> (alias <B>-force</B>) parameter.  (This is a
       new feature in 2.15)  This forces the default value to be used,
       regardless of the previous value of the field:
       <PRE>
       print $query-&gt;textfield(-name=&gt;'favorite_color',
                               -default=&gt;'red',
			       -override=&gt;1);
       </PRE>
</OL>
If you want to reset all fields to their defaults, you can:
<OL>
  <LI>Create a special <VAR>defaults</VAR> button using the <STRONG>defaults()</STRONG> method.
  <LI>Create a hypertext link that calls your script without any parameters.
</OL>
<EM>General note 3.</EM> You can put multiple forms on the same page if you
wish.  However, be warned that it isn't always easy to preserve state information
for more than one form at a time. See <A HREF="#advanced">advanced techniques</A>
for some hints.
<P>
<EM>General note 4.</EM> By popular demand, the text and labels that you
provide for form elements are escaped according to HTML rules.  This means
that you can safely use "&lt;CLICK ME&gt;" as the label for a button. However,
this behavior may interfere with your ability to incorporate special HTML
character sequences, such as &amp;Aacute; (&Aacute;) into your fields.  If
you wish to turn off automatic escaping, call the <CODE>autoEscape()</CODE>
method with a false value immediately after creating the CGI object:

<PRE>
     $query = new CGI;
     $query-&gt;autoEscape(undef);
</PRE>

You can turn autoescaping back on at any time with <CODE>$query-&gt;autoEscape('yes')</CODE>

<H3>Form Elements</H3>
<MENU>
  <LI><A HREF="#startform">Opening a form</A>
  <LI><A HREF="#textfield">Text entry fields</A>
  <LI><A HREF="#textarea">Big text entry fields</A>
  <LI><A HREF="#password">Password fields</A>
  <LI><A HREF="#upload">File upload fields</A>
  <LI><A HREF="#menu">Popup menus</A>
  <LI><A HREF="#scrolling_list">Scrolling lists</A>
  <LI><A HREF="#checkbox_group">Checkbox groups</A>
  <LI><A HREF="#checkbox">Individual checkboxes</A>
  <LI><A HREF="#radio">Radio button groups</A>
  <LI><A HREF="#submit">Submission buttons</A>
  <LI><A HREF="#reset">Reset buttons</A>
  <LI><A HREF="#defaults">Reset to defaults button</A>
  <LI><A HREF="#hidden">Hidden fields</A>
  <LI><A HREF="#image">Clickable Images</A>
  <LI><A HREF="#button">JavaScript Buttons</A>
  <LI><A HREF="#escape">Autoescaping HTML</A>
</MENU>
<A HREF="#contents">Up to table of contents</A>
<A NAME="isindex">
<H3>Creating An Isindex Tag</H3>
</A>
<PRE>
   print $query-&gt;isindex($action);
</PRE>
<STRONG>isindex()</STRONG> without any arguments returns an
&lt;ISINDEX&gt; tag that designates your script as the URL to call.
If you want the browser to call a different URL to handle the search,
pass isindex() the URL you want to be called.

<A NAME="startform">
<H3>Starting And Ending A Form</H3>
</A>
<PRE>
   print $query-&gt;startform($method,$action,$encoding);
     <VAR>...various form stuff...</VAR>
   print $query-&gt;endform;
</PRE>
<STRONG>startform()</STRONG> will return a &lt;FORM&gt; tag with the
optional method, action and form encoding that you specify.
<STRONG>endform()</STRONG> returns a &lt;/FORM&gt; tag.

<P>
The form encoding is a new feature introduced in version 1.57 in order
to support the "file upload" feature of Netscape 2.0.  The form encoding
tells the browser how to package up the contents of the form in order
to transmit it across the Internet.  There are
two types of encoding that you can specify:

<DL>
  <DT> <STRONG>application/x-www-form-urlencoded</STRONG>
  <DD> This is the type of encoding used by all browsers prior to
       Netscape 2.0.  It is compatible with many CGI scripts and is
       suitable for short fields containing text data.  For your
       convenience, CGI.pm stores the name of this encoding
       type in <CODE>$CGI::URL_ENCODED</CODE>.
  <DT> <STRONG>multipart/form-data</STRONG>
  <DD> This is the newer type of encoding introduced by Netscape 2.0.
       It is suitable for forms that contain very large fields or that
       are intended for transferring binary data.  Most importantly,
       it enables the "file upload" feature of Netscape 2.0 forms.  For
       your convenience, CGI.pm stores the name of this encoding type
       in <CODE>$CGI::MULTIPART</CODE>
       <P>
       Forms that use this type of encoding are not easily interpreted
       by CGI scripts unless they use CGI.pm or another library that
       knows how to handle them.  Unless you are using the file upload
       feature, there's no particular reason to use this type of encoding.
</DL>

For compatability, the startform() method uses the older form of
encoding by default.  If you want to use the newer form of encoding
By default, you can call <A HREF="#multipart">start_multipart_form()</A>
instead of <CODE>startform()</CODE>.

<p>

If you plan to make use of the <a href="#javascripting">JavaScript features</a>
of Netscape 2.0, you can provide <code>startform()</code> with the optional
<code>-name</code> and/or <code>-onSubmit</code>
parameters.  <code>-name</code> has no effect on the display of the
form, but can be used to give the form an identifier so that it can
be manipulated by JavaScript functions.  Provide the
<code>-onSubmit</code> parameter in order to register some JavaScript code
to be performed just before the form is submitted.  This is useful for
checking the validity of a form before submitting it.
Your JavaScript code should return a value of "true" to let Netscape
know that it can go ahead and submit the form, and "false" to abort
the submission.

<A NAME="multipart">
<H3>Starting a Form that Uses the Netscape 2.0 "File Upload" Feature</H3>
</A>
<PRE>
   print $query-&gt;start_multipart_form($method,$action,$encoding);
     <VAR>...various form stuff...</VAR>
   print $query-&gt;endform;
</PRE>
This has exactly the same usage as <CODE>startform()</CODE>, but
it specifies form encoding type <CODE>multipart/form-data</CODE>
as the default.

<A NAME="textfield">
<H3>Creating A Text Field</H3>
</A>
<PRE>
  <EM>Named parameter style</EM>
  print $query-&gt;textfield(-name=&gt;'field_name',
	                    -default=&gt;'starting value',
	                    -size=&gt;50,
	                    -maxlength=&gt;80);

   <EM>Old style</EM>
  print $query-&gt;textfield('foo','starting value',50,80);
</PRE>
<STRONG>textfield()</STRONG> will return a text input field.
<UL>
  <LI>The first parameter (<strong>-name</strong>) is the required name for the field.
  <LI>The optional second parameter (<strong>-default</strong>) is the starting value
       for the field contents.
  <LI>The optional third parameter (<strong>-size</strong>) is the size of the field in
       characters.
  <LI>The optional fourth parameter (<strong>-maxlength</strong>) is the
       maximum number of characters the field will accomodate.
</UL>
As with all these methods, the field will be initialized with its 
previous contents from earlier invocations of the script.  If you
want to force in the new value, overriding the existing one, see
<A HREF="#overriding">General note 2</A>.
<P>
When the form is processed, the value of the text field can be
retrieved with:
<PRE>
      $value = $query-&gt;param('foo');
</PRE>
<p>
<strong>JavaScripting:</strong> You can also provide
<strong>-onChange, -onFocus, -onBlur</strong> and
<strong>-onSelect</strong> parameters to register <a href="#javascripting">
JavaScript</a> event handlers.

<A NAME="textarea">
<H3>Creating A Big Text Field</H3>
</A>
<PRE>
   <EM>Named parameter style</EM>
   print $query-&gt;textarea(-name=&gt;'foo',
	 		  -default=&gt;'starting value',
	                  -rows=&gt;10,
	                  -columns=&gt;50);

   <EM>Old style</EM>
   print $query-&gt;textarea('foo','starting value',10,50);
</PRE>
<STRONG>textarea()</STRONG> is just like textfield(), but it allows you to specify
rows and columns for a multiline text entry box.  You can provide
a starting value for the field, which can be long and contain
multiple lines.
<p>
<strong>JavaScripting:</strong> Like textfield(), you can provide <strong>-onChange, -onFocus,
-onBlur</strong> and <strong>-onSelect</strong> parameters to register <a href="#javascripting">
JavaScript</a> event handlers.

<A NAME="password">
<H3>Creating A Password Field</H3>
</A>
<PRE>
   <EM>Named parameter style</EM>
   print $query-&gt;password_field(-name=&gt;'secret',
				-value=&gt;'starting value',
				-size=&gt;50,
				-maxlength=&gt;80);

   <EM>Old style</EM>
   print $query-&gt;password_field('secret','starting value',50,80);
</PRE>
<STRONG>password_field()</STRONG> is identical to textfield(), except that its contents 
will be starred out on the web page.

<A NAME="upload">
<H3>Creating a File Upload Field</H3>
</A>
<PRE>
    <EM>Named parameters style</EM>
    print $query-&gt;filefield(-name=&gt;'uploaded_file',
	                    -default=&gt;'starting value',
	                    -size=&gt;50,
	 		    -maxlength=&gt;80);

    <EM>Old style</EM>
    print $query-&gt;filefield('uploaded_file','starting value',50,80);
</PRE>
<STRONG>filefield()</STRONG> will return a form field that prompts the user
to upload a file.
<UL>
  <LI>The first parameter (<strong>-name</strong>) is the required name for the field.
  <LI>The optional second parameter (<strong>-default</strong>) is the starting value
       for the file name.
       This field is currently ignored by Netscape 2.0, but there's
       always hope!
  <LI>The optional third parameter (<strong>-size</strong>) is the size of the field in
       characters.
  <LI>The optional fourth parameter (<strong>-maxlength</strong>) is the
       maximum number of characters the field will accomodate.
</UL>

filefield() will return a file upload field for use with
Netscape 2.0 browsers.  Netscape will prompt the remote
user to select a file to transmit over the Internet to the
server.  Other browsers currently ignore this
field.

<P>

In order to take full advantage of the file upload
facility you must use the new <A HREF="#multipart">multipart
form encoding scheme</A>.  You can do this either
by calling <A HREF="#startform">startform()</A>
and specify an encoding type of <CODE>$CGI::MULTIPART</CODE>
or by using the new <A HREF="#multipart">start_multipart_form()</A>
method.  If you don't use multipart encoding, then you'll be
able to retreive the name of the file selected by the remote
user, but you won't be able to access its contents.

<P>

When the form is processed, you can retrieve the entered filename
by calling param().

<PRE>
       $filename = $query-&gt;param('uploaded_file');
</PRE>

where "uploaded_file" is whatever you named the file upload field.
Under Netscape 2.0beta1 the filename that gets returned is the full
local filename
on the <STRONG>remote user's</STRONG> machine.  If the remote
user is on a Unix machine, the filename will follow Unix conventions:

<PRE>
	/path/to/the/file
</PRE>

On an MS-DOS/Windows machine, the filename will follow DOS conventions:
<PRE>
	C:\PATH\TO\THE\FILE.MSW
</PRE>

On a Macintosh machine, the filename will follow Mac conventions:

<PRE>
	HD 40:Desktop Folder:Sort Through:Reminders
</PRE>

Netscape 2.0beta2 changes this behavior and only returns the name
of the file itself.  Who knows what the behavior of the release
browser will be?

<P>

The filename returned is also a file handle.  You can read the contents
of the file using standard Perl file reading calls:
<PRE>
	# Read a text file and print it out
	while (&lt;$filename&gt;) {
	   print;
        }

        # Copy a binary file to somewhere safe
        open (OUTFILE,"&gt;&gt;/usr/local/web/users/feedback");
	while ($bytesread=read($filename,$buffer,1024)) {
	   print OUTFILE $buffer;
        }
       close $filename;
</PRE>

You can have several file upload fields in the same form, and even
give them the same name if you like (in the latter case <CODE>param()</CODE>
will return a list of file names).

<P>

When processing an uploaded file, CGI.pm creates a temporary file on
your hard disk and passes you a file handle to that file.  After you
are finished with the file handle, CGI.pm unlinks (deletes) the
temporary file.  If you need to you can access the temporary file
directly.  Its name is stored inside the CGI object's "private" data,
and you can access it by passing the file name to the
<a name="tmpfilename">tmpFileName()</a> method:

<pre>
       $filename = $query-&gt;param('uploaded_file');
       $tmpfilename = $query-&gt;tmpFileName($filename);
</pre>

<p>

The temporary file will be deleted automatically when your program
exits unless you manually rename it.  On some operating systems (such
as Windows NT), you will need to close the temporary file's filehandle
before your program exits.  Otherwise the attempt to delete the
temporary file will fail.

<p>

A potential problem with the temporary file upload feature is that the
temporary file is accessible to any local user on the system.  In
previous versions of this module, the temporary file was world
readable, meaning that anyone could peak at what was being uploaded.
As of version 2.36, the modes on the temp file have been changed to
read/write by owner only.  Only the Web server and its CGI scripts can
access the temp file.  Unfortunately this means that one CGI script
can spy on another!  To make the temporary files
<strong>really</strong> private, set the CGI global variable
$CGI::PRIVATE_TEMPFILES to 1.  Alternatively, call the built-in
function CGI::private_tempfiles(1), or just <cite>use CGI
qw/:private_tempfiles</cite>.  The temp file will now be unlinked as
soon as it is created, making it inaccessible to other users.  The
<strong>downside</strong> of this is that you will be unable to obtain
the name of the temporary file using <cite>tmpFileName()</cite>.  This
function will return an empty string.  Further, since
PRIVATE_TEMPFILES is a global variable, its setting will affect all
instances of CGI.pm if you are running mod_perl.  You can work around
this limitation by declaring $CGI::PRIVATE_TEMPFILES as a local at the
top of your script.

<p>

Usually the browser sends along some header information along with the
text of the file itself. Currently the headers contain only the
original file name and the MIME content type (if known). Future
browsers might send other information as well (such as modification
date and size). To retrieve this information, call
<strong>uploadInfo()</strong>.  It returns a reference to an
associative array containing all the document headers.  For example,
this code fragment retrieves the MIME type of the uploaded file (be
careful to use the proper capitalization for "Content-Type"!):

<pre>
       $filename = $query->param('uploaded_file');
       $type = $query->uploadInfo($filename)->{'Content-Type'};
       unless ($type eq 'text/html') {
	  die "HTML FILES ONLY!";
       }
</pre>

<p>

<strong>JavaScripting:</strong> Like textfield(), filefield()
accepts <strong>-onChange, -onFocus, -onBlur</strong> and
<strong>-onSelect</strong> parameters to register <a href="#javascripting">
JavaScript</a> event handlers.

<A HREF="#upload_caveats">Caveats and potential problems in
the file upload feature.</A>

<A NAME="menu">
<H3>Creating A Popup Menu</H3>
</A>
<PRE>
  <EM>Named parameter style</EM>
  print $query-&gt;popup_menu(-name=&gt;'menu_name',
			    -values=&gt;['eenie','meenie','minie'],
	                    -default=&gt;'meenie',
	                    -labels=&gt;{'eenie'=&gt;'one','meenie'=&gt;'two',
                                      'minie'=&gt;'three'});
  
  <EM>Old style</EM>
  print $query-&gt;popup_menu('menu_name',
                              ['eenie','meenie','minie'],'meenie',
                              {'eenie'=&gt;'one','meenie'=&gt;'two','minie'=&gt;'three'});
</PRE>

<STRONG>popup_menu()</STRONG> creates a menu.
<UL>
  <LI>The required first argument (<strong>-name</strong>) is the menu's name.
  <LI>The required second argument (<strong>-values</strong>) is an array
       <EM>reference</EM> containing the list
       of menu items in the menu.  You can pass the method an anonymous 
       array, as shown in the example, or a reference to a named array,
       such as <TT>\@foo</TT>
  <LI>The optional third parameter (<strong>-default</strong>) is the name of the
       default menu choice.  
       If not specified, the first item will be the default.  The value of 
       the previous choice will be maintained across queries.
  <LI>The optional fourth parameter (<strong>-labels</strong>) allows you
       to pass a reference to an associative array containing user-visible
       labels for one or more of the menu items.  You can use this when you
       want the user to see one menu string, but have the browser return your
       program a different one.  If you don't specify this, the value string
       will be used instead ("eenie", "meenie" and "minie" in this example).
</UL>
When the form is processed, the selected value of the popup menu can
be retrieved using:
<PRE>
     $popup_menu_value = $query-&gt;param('menu_name');
</PRE>

<strong>JavaScripting:</strong> You can provide <code>-onChange,
-onFocus, and -onBlur</code>
parameters to register <a href="#javascripting">JavaScript</a> event
handlers.

<A NAME="scrolling_list">
<H3>Creating A Scrolling List</H3>
</A>
<PRE>
   <EM>Named parameter style</EM>
   print $query-&gt;scrolling_list(-name=&gt;'list_name',
                                -values=&gt;['eenie','meenie','minie','moe'],
                                -default=&gt;['eenie','moe'],
	                        -size=&gt;5,
	                        -multiple=&gt;'true',
                                -labels=&gt;\%labels);

   <EM>Old style</EM>
   print $query-&gt;scrolling_list('list_name',
                                ['eenie','meenie','minie','moe'],
                                ['eenie','moe'],5,'true',
                                \%labels);

</PRE>
<STRONG>scrolling_list()</STRONG> creates a scrolling list.
<UL>
  <LI>The first and second arguments (<strong>-name, -values</strong>)are the list name
       and values, respectively.  As in the popup menu, the second argument should 
       be an array reference.
  <LI>The optional third argument (<strong>-default</strong>)can be either a reference
       to a list containing the values to be selected by default, or can be a 
       single value to select.  If this argument is missing or undefined,
       then nothing is selected when the list first appears.
  <LI>The optional fourth argument (<strong>-size</strong>) is the display size of the list.
  <LI>The optional fifth argument (<strong>-multiple</strong>) can be set to true to allow multiple
       simultaneous selections.
  <LI>The option sixth argument (<strong>-labels</strong>) can be used to assign user-visible labels
       to the list items different from the ones used for the values as above.
       In this example we assume that an associative array <CODE>%labels</CODE>
       has already been created.
</UL>
When this form is processed, all selected list items will be returned as
a list under the parameter name 'list_name'.  The values of the
selected items can be retrieved with:
<PRE>
     @selected = $query-&gt;param('list_name');
</PRE>

<strong>JavaScripting:</strong> You can provide <strong>-onChange,
-onFocus,</strong> and <strong>-onBlur</strong>
parameters to register <a href="#javascripting">JavaScript</a> event
handlers.

<A NAME="checkbox_group">
<H3>Creating A Group Of Related Checkboxes</H3>
</A>
<PRE>
   <EM>Named parameter style</EM>
   print $query-&gt;checkbox_group(-name=&gt;'group_name',
                                -values=&gt;['eenie','meenie','minie','moe'],
                                -default=&gt;['eenie','moe'],
	                        -linebreak=&gt;'true',
	                        -labels=&gt;\%labels);

   <EM>Old Style</EM>
   print $query-&gt;checkbox_group('group_name',
                                ['eenie','meenie','minie','moe'],
                                ['eenie','moe'],'true',\%labels);

   <EM>HTML3 Browsers Only</EM>
   print $query-&gt;checkbox_group(-name=&gt;'group_name',
                                -values=&gt;['eenie','meenie','minie','moe'],
                                -rows=&gt;2,-columns=&gt;2);
</PRE>
<STRONG>checkbox_group()</STRONG> creates a list of checkboxes that are related
  by the same name.
<UL>
  <LI>The first and second arguments (<strong>-name, -values</strong>) are the checkbox
       name and values, 
       respectively.  As in the popup menu, the second argument should 
       be an array reference.  These values are used for the user-readable
       labels printed next to the checkboxes as well as for the values
       passed to your script in the query string.
  <LI>The optional third argument (<strong>-default</strong>) can be either a
       reference to a list
       containing the values to be checked by default, or can be a 
       single value to checked.  If this argument is missing or undefined,
       then nothing is selected when the list first appears.
  <LI>The optional fourth argument (<strong>-linebreak</strong>) can be set to true to
       place line breaks
       between the checkboxes so that they appear as a vertical list.
       Otherwise, they will be strung together on a horizontal line.
       When the form is procesed, all checked boxes will be returned as
       a list under the parameter name 'group_name'.  The values of the
       "on" checkboxes can be retrieved with:
  <LI>The optional fifth argument (<strong>-labels</strong>) is a reference to an associative array
       of checkbox labels.  This allows you to use different strings for
       the user-visible button labels and the values sent to your script.  In
       this example we assume that an associative array <CODE>%labels</CODE>
       has previously been created.
 <LI>The optional parameter <STRONG>-nolabels</STRONG> can be used to
     suppress the printing of labels next to the button.  This is
     useful if you want to capture the button elements individually and use them
     inside labeled HTML3 tables.
  <LI><STRONG>Browsers that understand HTML3 tables</STRONG>
       (such as Netscape) can take advantage of the optional 
       parameters <STRONG>-rows</STRONG>, and <STRONG>-columns</STRONG>.
       These parameters cause
       checkbox_group() to return an HTML3 compatible table containing
       the checkbox group formatted with the specified number of rows
       and columns.  You can provide just the -columns parameter if you
       wish; checkbox_group will calculate the correct number of rows
       for you.
       <P>
       To include row and column headings in the returned table, you
       can use the <STRONG>-rowheaders</STRONG> and <STRONG>-colheaders</STRONG>
       parameters.  Both
       of these accept a pointer to an array of headings to use.
       The headings are just decorative.  They don't reorganize the
       interpetation of the checkboxes -- they're still a single named
       unit.
       <P>
       When viewed with browsers that don't understand HTML3 tables, the
       -rows and -columns parameters will leave you
       with a group of buttons that may be awkwardly formatted but
       still useable. However, if you add row
       and/or column headings, the resulting text will be very hard to
       read.
</UL>
When the form is processed, the list of checked buttons in the group
can be retrieved like this:
<PRE>
     @turned_on = $query-&gt;param('group_name');
</PRE>

This function actually returns an array of button elements.  You can
capture the array and do interesting things with it, such as incorporating
it into your own tables or lists.  The <strong>-nolabels</strong> option
is also useful in this regard:
<PRE>
       @h = $query-&gt;checkbox_group(-name=&gt;'choice',
                                    -value=&gt;['fee','fie','foe'],
                                    -nolabels=&gt;1);
       create_nice_table(@h);
</PRE>

<strong>JavaScripting:</strong> You can provide an <strong>-onClick</strong>
parameter to register some <a href="#javascripting">JavaScript</a>
code to be performed every time the user clicks on any of the buttons
in the group.

<A NAME="checkbox">
<H3>Creating A Standalone Checkbox</H3>
</A>
<PRE>
   <EM>Named parameter list</EM>
   print $query-&gt;checkbox(-name=&gt;'checkbox_name',
			   -checked=&gt;'checked',
		           -value=&gt;'TURNED ON',
		           -label=&gt;'Turn me on');

   <EM>Old style</EM>
   print $query-&gt;checkbox('checkbox_name',1,'TURNED ON','Turn me on');
</PRE>
<STRONG>checkbox()</STRONG> is used to create an isolated checkbox that isn't logically
related to any others.
<UL>
  <LI>The first parameter (<STRONG>-name</STRONG> is the required name
       for the checkbox.  It
       will also be used for the user-readable label printed next to
       the checkbox.
  <LI>The optional second parameter (<STRONG>-checked</STRONG> specifies
       that the checkbox is turned on by default.  Aliases for this
       parameter are <STRONG>-selected</STRONG> and <STRONG>-on</STRONG>.
  <LI>The optional third parameter (<STRONG>-value</STRONG> specifies
       the value of the checkbox
       when it is checked.  If not provided, the word "on" is assumed.
  <LI>The optional fourth parameter (<STRONG>-label</STRONG> assigns a
       user-visible label to the button.
       If not provided, the checkbox's name will be used.
</UL>
The value of the checkbox can be retrieved using:
<PRE>
     $turned_on = $query-&gt;param('checkbox_name');
</PRE>

<strong>JavaScripting:</strong> You can provide an <code>-onClick</code>
parameter to register some <a href="#javascripting">JavaScript</a>
code to be performed every time the user clicks on the button.

<A NAME="radio">
<H3>Creating A Radio Button Group</H3>
</A>
<PRE>
   <EM>Named parameter style</EM>
   print $query-&gt;radio_group(-name=&gt;'group_name',
			     -values=&gt;['eenie','meenie','minie'],
                             -default=&gt;'meenie',
			     -linebreak=&gt;'true',
			     -labels=&gt;\%labels);

   <EM>Old style</EM>
   print $query-&gt;radio_group('group_name',['eenie','meenie','minie'],
                                          'meenie','true',\%labels);

   <EM>HTML3-compatible browsers only</EM>
   print $query-&gt;radio_group(-name=&gt;'group_name',
                                -values=&gt;['eenie','meenie','minie','moe'],
	                        -rows=2,-columns=&gt;2);
</PRE>

<STRONG>radio_group()</STRONG> creates a set of logically-related radio buttons.
  Turning one member of the group on turns the others off.
<UL>
  <LI>The first argument (<STRONG>-name</STRONG> is the name of the
       group and is required.
  <LI>The second argument (<STRONG>-values</STRONG> is the list of
       values for the radio buttons.
       The values and the labels that appear on the page are identical.
       Pass an array <EM>reference</EM> in the second argument, either using 
       an anonymous array, as shown, or by referencing a named array as 
       in <CODE>\@foo</CODE>.
  <LI>The optional third parameter (<STRONG>-default</STRONG> is the
       value of the default button to
       turn on. If not specified, the first item will be the default.  Specify
       some nonexistent value, such as "-" if you don't want any button
       to be turned on.
  <LI>The optional fourth parameter (<STRONG>-linebreak</STRONG> can be
       set to 'true' to put
       line breaks between the buttons, creating a vertical list.
  <LI>The optional fifth parameter (<STRONG>-labels</STRONG> specifies
       an associative array containing labels to be printed next to
       each the button.  If not provided the button value will be
       used instead.  This example assumes that the associative array
       <CODE>%labels</CODE> has already been defined.
 <LI>The optional parameter <STRONG>-nolabels</STRONG> can be used to
     suppress the printing of labels next to the button.  This is
     useful if you want to capture the button elements individually and use them
     inside labeled HTML3 tables.
  <LI><STRONG>Browsers that understand HTML3 tables</STRONG>
       (such as Netscape) can take advantage of the optional 
       parameters <STRONG>-rows</STRONG>, and <STRONG>-columns</STRONG>.
       These parameters cause
       radio_group() to return an HTML3 compatible table containing
       the radio cluster formatted with the specified number of rows
       and columns.  You can provide just the -columns parameter if you
       wish; radio_group will calculate the correct number of rows
       for you.
       <P>
       To include row and column headings in the returned table, you
       can use the <STRONG>-rowheader</STRONG> and <STRONG>-colheader</STRONG>
       parameters.  Both
       of these accept a pointer to an array of headings to use.
       The headings are just decorative.  They don't reorganize the
       interpetation of the radio buttons -- they're still a single named
       unit.
       <P>
       When viewed with browsers that don't understand HTML3 tables, the
       -rows and -columns parameters will leave you
       with a group of buttons that may be awkwardly formatted but
       still useable. However, if you add row
       and/or column headings, the resulting text will be very hard to
       read.
</UL>
When the form is processed, the selected radio button can
be retrieved using:
<PRE>
       $which_radio_button = $query-&gt;param('group_name');
</PRE>
This function actually returns an array of button elements.  You can
capture the array and do interesting things with it, such as incorporating
it into your own tables or lists  The <strong>-nolabels</strong> option
is useful in this regard.:
<PRE>
       @h = $query-&gt;radio_group(-name=&gt;'choice',
                                 -value=&gt;['fee','fie','foe'],
                                 -nolabels=&gt;1);
       create_nice_table(@h);
</PRE>

<p>
<strong>JavaScripting</strong>: You can provide an <strong>-onClick</strong>
parameter to register some <a href="#javascripting">JavaScript</a>
code to be performed every time the user clicks on any of the buttons
in the group.

<A NAME="submit"><H3>
Creating A Submit Button</H3>
</A>
<PRE>
   <EM>Named parameter style</EM>
   print $query-&gt;submit(-name=&gt;'button_name',
		        -value=&gt;'value');

  <EM>Old style</EM>
  print $query-&gt;submit('button_name','value');
</PRE>
<STRONG>submit()</STRONG> will create the query submission button.  Every form
    should have one of these.
<UL>
  <LI>The first argument (<STRONG>-name</STRONG>is optional.
       You can give the button a
       name if you have several submission buttons in your form and
       you want to distinguish between them.
  <LI>The second argument (<STRONG>-value</STRONG>is also optional.
      This gives the button
      a value that will be passed to your script in the query string,
      and will also appear as the user-visible label.
      <p>
      You can figure out which of several buttons was pressed by using
      different values for each one:
<PRE>
    $which_one = $query-&gt;param('button_name');
</PRE>

  <LI>You can use <strong>-label</strong> as an alias for
      <strong>-value</strong>.  I always get confused about which of
      <code>-name</code> and <code>-value</code> changes the user-visible
      label on the button.
</UL>

<strong>JavaScripting:</strong> You can provide an <strong>-onClick</strong>
parameter to register some <a href="#javascripting">JavaScript</a>
code to be performed every time the user clicks on the button.
You can't prevent a form from being submitted, however.  You must
provide an <strong>-onSubmit</strong> handler to the <a href="#">form
itself</a> to do that.

<A NAME="reset">
<H3>Creating A Reset Button</H3>
</A>
<PRE>
  print $query-&gt;reset
</PRE>
<STRONG>reset()</STRONG> creates the "reset" button.  It undoes whatever
changes the user has recently made to the form, but does <STRONG>not</STRONG>
 necessarily reset the form all the way to the defaults.  See <STRONG>defaults()</STRONG>
 for that.  It takes the optional label for the button ("Reset" by default).

<strong>JavaScripting:</strong> You can provide an <strong>-onClick</strong>
parameter to register some <a href="#javascripting">JavaScript</a>
code to be performed every time the user clicks on the button.

<A NAME="defaults">
<H3>Creating A Defaults Button</H3>
</A>
<PRE>
  print $query-&gt;defaults('button_label')
</PRE>
<STRONG>defaults()</STRONG> creates "reset to defaults" button.
It takes the optional label for the button ("Defaults" by default).
When the user presses this button, the form will automagically
be cleared entirely and set to the defaults you specify in your
script, just as it was the first time it was called.

<A NAME="hidden">
<H3>Creating A Hidden Field</H3>
</A>
<PRE>
   <EM>Named parameter style</EM>
   print $query-&gt;hidden(-name=&gt;'hidden_name',
                        -default=&gt;['value1','value2'...]);

   <EM>Old style</EM>
   print $query-&gt;hidden('hidden_name','value1','value2'...);
</PRE>
<STRONG>hidden()</STRONG> produces a text field that can't be seen by the user.  It
is useful for passing state variable information from one invocation
of the script to the next.
<UL>
  <LI>The first argument (<STRONG>-name</STRONG>) is required and
       specifies the name of this field.
  <LI>The second and subsequent arguments specify the value for the hidden field.
       This is a quick and dirty way of passing perl arrays through forms.  If
       you use the named parameter style, you must provide the parameter
       <STRONG>-default</STRONG> and an array reference here.
</UL>
<STRONG><A NAME="hidden_fields_warning">
<IMG SRC="examples/caution.xbm" ALT="[CAUTION]">
As of version 2.0 I have changed the behavior of hidden fields
once again.  Read this if you use hidden fields.</A></STRONG>
<P>
Hidden fields used to behave differently from all other fields: the
provided default values always overrode the "sticky" values.  This was the
behavior people seemed to expect, however it turns out to make it harder
to write state-maintaining forms such as shopping cart programs.  Therefore
I have made the behavior consistent with other fields.
<P>
Just like all the other form elements, the value of a
hidden field is "sticky".  If you want to replace a hidden field with
some other values after the script has been called once you'll have to
do it manually before writing out the form element:
<PRE>
     $query-&gt;param('hidden_name','new','values','here');
     print $query-&gt;hidden('hidden_name');
</PRE>

Fetch the value of a hidden field this way:
<PRE>
    $hidden_value = $query-&gt;param('hidden_name');
            -or (for values created with arrays)-
    @hidden_values = $query-&gt;param('hidden_name');
</PRE>

<A NAME="image">
<H3>Creating a Clickable Image Button</H3>
</A>
<PRE>
   <EM>Named parameter style</EM>
   print $query-&gt;image_button(-name=&gt;'button_name',
                              -src=&gt;'/images/NYNY.gif',
                              -align=&gt;'MIDDLE');	

   <EM>Old style</EM>
   print $query-&gt;image_button('button_name','/source/URL','MIDDLE');

</PRE>
<STRONG>image_button()</STRONG> produces an inline image that acts as
a submission button.  When selected, the form is submitted and the
clicked (x,y) coordinates are submitted as well.
<UL>
  <LI>The first argument(<STRONG>-name</STRONG> is required and
       specifies the name of this
       field.
  <LI>The second argument (<STRONG>-src</STRONG>specifies the URL of
       the image to display.  It
       must be one of the types supported by inline images (e.g. GIF), but
       can be any local or remote URL.
  <LI>The third argument (<STRONG>-align</STRONG>is anything you might
       want to use in the ALIGN attribute, such as
       TOP, BOTTOM, LEFT, RIGHT or MIDDLE.  This field is optional.
</UL>

When the image is clicked, the results are passed to your script in two
parameters named "button_name.x" and "button_name.y", where "button_name"
is the name of the image button.
<PRE>
    $x = $query-&gt;param('button_name.x');
    $y = $query-&gt;param('button_name.y');
</PRE>

<strong>JavaScripting:</strong> You can provide an <code>-onClick</code>
parameter to register some <a href="#javascripting">JavaScript</a>
code to be performed every time the user clicks on the button.

<A NAME="button">
<H3>Creating a JavaScript Button</H3>
</A>
<PRE>
   <EM>Named parameter style</EM>
   print $query-&gt;button(-name=&gt;'button1',
                           -value=&gt;'Click Me',
                           -onClick=&gt;'doButton(this)');	

   <EM>Old style</EM>
   print $query-&gt;image_button('button1','Click Me','doButton(this)');

</PRE>
<STRONG>button()</STRONG> creates a JavaScript button.  When the button is
pressed, the JavaScript code pointed to by the <code>-onClick</code> parameter
is executed.  This only works with Netscape 2.0 and higher.  Other browsers
do not recognize JavaScript and probably won't even display the button.
<UL>
  <LI>The first argument(<STRONG>-name</STRONG> is required and
       specifies the name of this field.
  <LI>The second argument (<STRONG>-value</STRONG> gives the button
      a value, and will be used as the user-visible label on the button.
  <LI>The third argument (<STRONG>-onClick</STRONG> is any valid
      JavaScript code.  It's usually a call to a JavaScript function
      defined somewhere else (see the <a href="#html">start_html()</a>
      method), but can be any JavaScript you like.  Multiple lines
      are allowed, but you must be careful not to include any double
      quotes in the JavaScript text.
</UL>
See <a href="#javascripting">JavaScripting</a> for more information.

<H3><A NAME="escape">Controlling HTML Autoescaping</A></H3>
By default, if you use a special HTML character such as &gt;, &lt;
or &amp; as the label or value of a button, it will be escaped
using the appropriate HTML escape sequence (e.g. &amp;gt;).  This
lets you use anything at all for the text of a form field without
worrying about breaking the HTML document.  However, it may also
interfere with your ability to use special characters, such as
&Aacute; as default contents of fields.  You can turn this
feature on and off with the method <CODE>autoEscape()</CODE>.
<P>
Use
<PRE>
    $query-&gt;autoEscape(undef);
</PRE>
to turn automatic HTML escaping off, and
<PRE>
    $query-&gt;autoEscape('true');
</PRE>
to turn it back on.

<HR>
<A NAME="import">
<H2>Importing CGI Methods</H2>
</A>

A large number of scripts allocate only a single query object, use it
to read parameters or to create a fill-out form, and then discard it.
For this type of script, it may be handy to import CGI module methods
into your name space.  The most common syntax for this is:

<blockquote><pre>
use CGI qw(:standard);
</pre></blockquote>

This imports the standard methods into your namespace.  Now instead of
getting parameters like this:

<blockquote><pre>
use CGI;
$dinner = $query-&gt;param('entree');
</pre></blockquote>

You can do it like this:

<blockquote><pre>
use CGI qw(:standard);
$dinner = param('entree');
</pre></blockquote>

Similarly, instead of creating a form like this:

<blockquote><pre>
print $query-&gt;start_form,
      "Check here if you're happy: ",
      $query-&gt;checkbox(-name=&gt;'happy',-value=&gt;'Y',-checked=&gt;1),
      "&lt;P&gt;",
      $query-&gt;submit,
      $query-&gt;end_form;
</pre></blockquote>

You can create it like this:

<blockquote><pre>
print start_form,
      "Check here if you're happy: ",
      checkbox(-name=&gt;'happy',-value=&gt;'Y',-checked=&gt;1),
      p,
      submit,
      end_form;
</pre></blockquote>

Even though there's no CGI object in view in the second example, state
is maintained using an implicit CGI object that's created
automatically.  The form elements created this way are sticky, just as
before.  If you need to get at the implicit CGI object directly, you
can refer to it as:

<blockquote><pre>
$CGI::Q;
</pre></blockquote>

<p>

The <strong>use CGI</strong> statement is used to import method names
into the current name space.  There is a slight overhead for each name
you import, but ordinarily is nothing to worry about.  You can import
selected method names like this:
<blockquote><pre>
   use CGI qw(header start_html end_html);
</pre></blockquote>

Ordinarily, however, you'll want to import groups of methods using
export tags.  Export tags refer to sets of logically related methods
which are imported as a group with <strong>use</strong>.  Tags are
distinguished from ordinary methods by beginning with a ":" character.
This example imports the methods dealing with the CGI protocol
(<code>param()</code> and the like) as well as shortcuts that generate
HTML2-compliant tags:

<blockquote>
<pre>
use CGI qw(:cgi :html2);
</pre>
</blockquote>

Currently there are 8 method families defined in CGI.pm.  They are:

<dl>
  <dt><cite>:cgi</cite>
  <dd>These are all the tags that support one feature or another of
      the CGI protocol, including param(), path_info(), cookie(),
      request_method(), header() and the like.
  <dt><cite>:form</cite>
  <dd>These are all the form element-generating methods, including
      start_form(), textfield(), etc.
  <dt><cite>:html2</cite>
  <dd>These are HTML2-defined shortcuts such as br(), p() and head().
      It also includes such things
      as start_html() and end_html() that aren't exactly HTML2, but
      are close enough.
  <dt><cite>:html3</cite>
  <dd>These are a few HTML3 extensions that are in common enough usage
      to be worth including.
  <dt><cite>:netscape</cite>
  <dd>These are Netscape extensions not included in the HTML3
      category, including frameset(), blink() and center().
  <dt><cite>:html</cite>
  <dd>These are all the HTML generating shortcuts, comprising the
      union of <cite>html2, html3,</cite> and <cite>netscape</cite>.
  <dt><cite>:standard</cite>
  <dd>This is the union of <cite>html2, form,</cite> and
      <cite>:cgi</cite> (everything except the HTML3 and
      Netscape extensions).
  <dt><cite>:all</cite>
  <dd>This imports all the public methods into your namespace!
</dl>

In addition to these method families, there is a special one named
<cite>:any</cite> that changes the behavior of the CGI query object.
If you import <cite>:any</cite>, then any method that the query object
doesn't recognize will be interpreted as a new HTML tag.  This allows
you to support the next <cite>ad hoc</cite> Netscape or Microsoft HTML
extension.  For example, to support Netscape's latest tag,
&lt;GRADIENT&gt; (which causes the user's desktop to be flooded with a
rotating gradient fill until his machine reboots), you can use
something like this:

<blockquote><pre>
use CGI qw(:any :all);
$q=new CGI;
print $q-&gt;gradient({speed=&gt;'fast',start=&gt;'red',end=&gt;'blue'});
</pre></blockquote>

Since using <cite>any</cite> causes any mistyped method name
to be interpreted as an HTML tag, use it with care or not at
all.

<HR>
<A NAME="debugging">
<H2>Debugging</H2>
</A>
If you are running the script
from the command line or in the perl debugger, you can pass the script
a list of keywords or parameter=value pairs on the command line or 
from standard input (you don't have to worry about tricking your
script into reading from environment variables).
You can pass keywords like this:
<PRE>
   my_script.pl keyword1 keyword2 keyword3
</PRE>
<EM>or this:</EM>
<PRE>
   my_script.pl keyword1+keyword2+keyword3
</PRE>
<EM>or this:</EM>
<PRE>
   my_script.pl name1=value1 name2=value2
</PRE>
<EM>or this:</EM>
<PRE>
   my_script.pl name1=value1&amp;name2=value2
</PRE>
or even by sending newline-delimited parameters to standard input:
<PRE>
   % my_script.pl
   first_name=fred
   last_name=flintstone
   occupation='granite miner'
   ^D
</PRE>
<P>When debugging, you can use quotation marks and the backslash
character to escape spaces and other funny characters in exactly
the way you would in the shell (which isn't surprising since CGI.pm
uses "shellwords.pl" internally).  This lets you do this sort of thing:
<PRE>
    my_script.pl "'name 1'='I am a long value'" "'name 2'=two\ words"
</PRE>

<A HREF="#contents">Table of contents</A>

<A NAME="dumping">
<H3>Dumping Out All The Name/Value Pairs</H3>
</A>
The <STRONG>dump()</STRONG> method produces a string consisting of all the query's
name/value pairs formatted nicely as a nested list.  This is useful
for debugging purposes:
<PRE>
   print $query-&gt;dump
</PRE>   
   Produces something that looks like this:
<PRE>
   &lt;UL&gt;
   &lt;LI&gt;name1
       &lt;UL&gt;
       &lt;LI&gt;value1
       &lt;LI&gt;value2
       &lt;/UL&gt;
   &lt;LI&gt;name2
       &lt;UL&gt;
       &lt;LI&gt;value1
       &lt;/UL&gt;
   &lt;/UL&gt;
</PRE>
You can achieve the same effect by incorporating the CGI object directly
into a string, as in:
<PRE>
   print "&lt;H2&gt;Current Contents:&lt;/H2&gt;\n$query\n";
</PRE>

<HR>
<A NAME="environment">
<H2>HTTP Session Variables</H2>
</A>
Some of the more useful environment variables can be fetched
through this interface.  The methods are as follows:
<DL>
  <DT>accept()   
  <DD>Return a list of MIME types that the remote browser
       accepts. If you give this method a single argument
       corresponding to a MIME type, as in
       <CODE>$query-&gt;accept('text/html')</CODE>, it will return a
       floating point value corresponding to the browser's
       preference for this type from 0.0 (don't want) to 1.0.
       Glob types (e.g. text/*) in the browser's accept list
       are handled correctly.
  <DT>auth_type()
  <DD>Return the authorization type, if protection is active.  Example "Basic".
  <DT><a name="raw_cookie">raw_cookie()</a>
  <DD>Returns the "magic cookie" maintained by Netscape 1.1 and higher in a raw
      state.  You'll probably want to use <a href="cookies">cookie()</a> instead,
      which gives you a high-level interface to the cookie functions.
  <DT><a name="path_info">path_info()</a>
  <DD>Returns additional path information from the script URL.
       E.G. fetching <CODE>/cgi-bin/your_script/additional/stuff</CODE> will
       result in <CODE>$query-&gt;path_info()</CODE> returning
       <CODE>"/additional/stuff"</CODE>
  <DT>path_translated()  
  <DD>As per path_info() but returns the additional
       path information translated into a physical path, e.g.
       <CODE>"/usr/local/etc/httpd/htdocs/additional/stuff"</CODE>.
  <DT>query_string()  
  <DD>Returns a query string suitable for maintaining state.
  <DT>referer()
  <DD>Return the URL of the page the browser was viewing
       prior to fetching your script.  Not available for all
       browsers.
  <DT>remote_addr()
  <DD>Return the dotted IP address of the remote host.
  <DT>remote_ident()
  <DD>Return the identity-checking information from the remote host.  Only
       available if the remote host has the identd daemon turned on.
  <DT>remote_host() 
  <DD>Returns either the remote host name or IP address.
       if the former is unavailable.
  <DT>remote_user()
  <DD>Return the name given by the remote user during password authorization.
  <DT>request_method()
  <DD>Return the HTTP method used to request your script's URL, usually
      one of <code>GET, POST,</code> or <code>HEAD</code>.
  <DT>script_name()
  <DD>Return the script name as a partial URL, for self-refering
       scripts.
  <DT>server_name()
  <DD>Return the name of the WWW server the script is running under.
  <DT>server_software()
  <DD>Return the name and version of the server software.
  <DT>virtual_host()
  <DD>When using the virtual host feature of some servers, returns the
      name of the virtual host the browser is accessing.
  <DT>server_port()
  <DD>Return the communications port the server is using.
  <DT>user_agent()
  <DD>Returns the identity of the remote user's browser software,
       e.g. "Mozilla/1.1N (Macintosh; I; 68K)"
  <DT>user_name()
  <DD>Attempts to obtain the remote user's name, using a variety
       of environment variables.  This only works with older browsers
       such as Mosaic.  Netscape does not reliably report the user
       name!
</DL>
<A HREF="#contents">Table of contents</A>

<HR>
<A NAME="cookies">
<H2>Netscape Cookies</H2>
</A>

Netscape browsers versions 1.1 and higher support a so-called
"cookie" designed to help maintain state within a browser session.
CGI.pm has several methods that support cookies.

<p>

A cookie is a name=value pair much like the named parameters in a CGI
query string.  CGI scripts create one or more cookies and send
them to the browser in the HTTP header.  The browser maintains a list
of cookies that belong to a particular Web server, and returns them
to the CGI script during subsequent interactions.

<p>

In addition to the required name=value pair, each cookie has several
optional attributes:

<dl>
  <dt>an expiration time
  <dd>This is a time/date string (in a special GMT format) that indicates
      when a cookie expires.  The cookie will be saved and returned to your
      script until this expiration date is reached if the user exits
      Netscape and restarts it.  If an expiration date isn't specified, the cookie
      will remain active until the user quits Netscape.<p>
  <dt>a domain
  <dd>This is a partial or complete domain name for which the cookie is 
      valid.  The browser will return the cookie to any host that matches
      the partial domain name.  For example, if you specify a domain name
      of ".capricorn.com", then Netscape will return the cookie to
      Web servers running on any of the machines "www.capricorn.com", 
      "www2.capricorn.com", "feckless.capricorn.com", etc.  Domain names
      must contain at least two periods to prevent attempts to match
      on top level domains like ".edu".  If no domain is specified, then
      the browser will only return the cookie to servers on the host the
      cookie originated from.<p>
  <dt>a path
  <dd>If you provide a cookie path attribute, the browser will check it
      against your script's URL before returning the cookie.  For example,
      if you specify the path "/cgi-bin", then the cookie will be returned
      to each of the scripts "/cgi-bin/tally.pl", "/cgi-bin/order.pl",
      and "/cgi-bin/customer_service/complain.pl", but not to the script
      "/cgi-private/site_admin.pl".  By default, path is set to "/", which
      causes the cookie to be sent to any CGI script on your site.
  <dt>a "secure" flag
  <dd>If the "secure" attribute is set, the cookie will only be sent to your
      script if the CGI request is occurring on a secure channel, such as SSL.
</dl>

The interface to Netscape cookies is the <strong>cookie()</strong> method:
<pre>
    $cookie = $query-&gt;cookie(-name=&gt;'sessionID',
			     -value=&gt;'xyzzy',
			     -expires=&gt;'+1h',
			     -path=&gt;'/cgi-bin/database',
			     -domain=&gt;'.capricorn.org',
			     -secure=&gt;1);
    print $query-&gt;header(-cookie=&gt;$cookie);
</pre>

<strong>cookie()</strong> creates a new cookie.  Its parameters include:

<dl>
  <dt><strong>-name</strong>
  <dd>The name of the cookie (required).  This can be any string at all.
      Although Netscape limits its cookie names to non-whitespace
      alphanumeric characters, CGI.pm removes this restriction by escaping
      and unescaping cookies behind the scenes.<p>
  <dt><strong>-value</strong>
  <dd>The value of the cookie.  This can be any scalar value,
      array reference, or even associative array reference.  For example,
      you can store an entire associative array into a cookie this way:
<pre>
	$cookie=$query-&gt;cookie(-name=&gt;'family information',
                               -value=&gt;\%childrens_ages);
</pre>
      
  <dt><strong>-path</strong>
  <dd>The optional partial path for which this cookie will be valid, as described
      above.<p>
  <dt><strong>-domain</strong>
  <dd>The optional partial domain for which this cookie will be valid, as described
      above.
  <dt><strong>-expires</strong>
  <dd>The optional expiration date for this cookie.  The format is as described 
      in the section on the <strong>header()</strong> method:
      <pre>
	"+1h"  one hour from now
      </pre>
  <dt><strong>-secure</strong>
  <dd>If set to true, this cookie will only be used within a secure
      SSL session.
</dl>

The cookie created by <strong>cookie()</strong> must be incorporated into the HTTP
header within the string returned by the <a href="#header">header()</a> method:
<pre>
	print $query-&gt;header(-cookie=&gt;$my_cookie);
</pre>
To create multiple cookies, give header() an array reference:
<pre>
	$cookie1 = $query-&gt;cookie(-name=&gt;'riddle_name',
                                  -value=&gt;"The Sphynx's Question");
        $cookie2 = $query-&gt;cookie(-name=&gt;'answers',
                                  -value=&gt;\%answers);
        print $query-&gt;header(-cookie=&gt;[$cookie1,$cookie2]);
</pre>

To retrieve a cookie, request it by name by calling cookie()
method without the <strong>-value</strong> parameter:

<pre>
	use CGI;
	$query = new CGI;
	%answers = $query-&gt;cookie('answers');
	# $query-&gt;cookie(-name=&gt;'answers') works too!
</pre>


To retrieve the names of all cookies passed to your script, call
<strong>cookie()</strong> without any parameters.  This allows you to
iterate through all cookies:

<pre>
	foreach $name ($query-&gt;cookie()) {
            print $query-&gt;cookie($name);
        }
</pre>

<p>

The cookie and CGI namespaces are separate.  If you have a parameter
named 'answers' and a cookie named 'answers', the values retrieved by
param() and cookie() are independent of each other.  However, it's
simple to turn a CGI parameter into a cookie, and vice-versa:

<pre>
   # turn a CGI parameter into a cookie
   $c=$q-&gt;cookie(-name=&gt;'answers',-value=&gt;[$q-&gt;param('answers')]);
   # vice-versa
   $q-&gt;param(-name=&gt;'answers',-value=&gt;[$q-&gt;cookie('answers')]);
</pre>

<p>
See the <a href="./examples/cookie.cgi">cookie.cgi</a> example script
for some ideas on how to use cookies effectively.
<p>

<strong>NOTE:</strong> There appear to be some (undocumented)
restrictions on Netscape cookies.  In Netscape 2.01, at least, I
haven't been able to set more than three cookies at a time.  There may
also be limits on the length of cookies.  If you need to store a lot
of information, it's probably better to create a unique session ID,
store it in a cookie, and use the session ID to locate an external
file/database saved on the server's side of the connection.
<p>
<A HREF="#contents">Table of contents</A>

<HR>

<A NAME="frames">
<H2>Support for Netscape Frames</H2>
</A>
CGI.pm contains support for
<a href="http://home.netscape.com/assist/net_sites/frames.html">Netscape frames</a>,
a new feature in version 2.0 and higher.  Frames are supported in two ways:
<ol>
  <li> You can direct the output of a script into a new window or into a
      preexisting named frame by providing the name of the frame as a
      <code>-target</code> argument in the header method.  For example,
      the following code will pop up a new Netscape window and display the script's
      output:
      <pre>
      $query = new CGI;
      print $query-&gt;header(-target=&gt;'_blank');
      </pre>
  <li> You can provide the name of a new or preexisting frame in the startform()
      and start_multipart_form() methods using the <code>-target</code>
      parameter.  When the form is submitted, the output
      will be redirected to the indicated frame:
      <pre>
      print $query-&gt;start_form(-target=&gt;'result_frame');
      </pre>
</ol>
Using frames effectively can be tricky.  To create a proper frameset in which
the query and response are displayed side-by-side requires you to
divide the script into three functional sections.  The first section should
create the &lt;frameset&gt; declaration and exit.  The second section is
responsible for creating the query form and directing it into the one
frame.  The third section is responsible for creating the response and directing
it into a different frame.
<p>
<a href="examples/">The examples directory</a> contains a script called
<a href="examples/popup.cgi">popup.cgi</a> that demonstrates a simple
popup window.  <a href="examples/frameset.cgi">frameset.cgi</a> provides
a skeleton script for creating side-by-side query/result frame sets.
<HR>

<A NAME="javascripting">
<H2>Support for JavaScript</H2>
</A>
Netscape versions 2.0 and higher incorporate an interpreted language
called JavaScript.  It isn't the same as Java, and certainly isn't at all
the same as Perl, which is a great pity.  JavaScript allows you to
programatically change the contents of fill-out forms, create new
windows, and pop up dialog box from within Netscape itself.  From the
point of view of CGI scripting, JavaScript is quite useful for
validating fill-out forms prior to submitting them.
<p>
You'll need to know JavaScript in order to use it.  The
<a href="http://home.netscape.com/eng/mozilla/2.0/handbook/javascript/">
Netscape JavaScript manual</a> contains
a good tutorial and reference guide to the JavaScript programming
language.
<p>
The usual way to use JavaScript is to define a set of functions in
a &lt;SCRIPT&gt; block inside the HTML header and then to register
event handlers in the various
elements of the page.  Events include such things as the mouse passing
over a form element, a button being clicked, the contents of a text
field changing, or a form being submitted.  When an event occurs
that involves an element that has registered an event handler, its
associated JavaScript code gets called.
<p>
The elements that can register event handlers include the &lt;BODY&gt;
of an HTML document, hypertext links, all the various elements of a
fill-out form, and the form itself.  There are a large number
of events, and each applies only to the elements for which it is relevant:
<dl>
  <dt><b>onLoad</b>
  <dd>The browser is loading the current document.  Valid in:
      <ul>
	<li>The HTML &lt;BODY&gt; section only.
      </ul>
  <dt><b>onUnload</b>
  <dd>The browser is closing the current page or frame.  Valid for:
      <ul>
	<li>The HTML &lt;BODY&gt; section only.
      </ul>
  <dt><b>onSubmit</b>
  <dd>The user has pressed the submit button of a form.  This event
      happens just before the form is submitted, and your function
      can return a value of <em>false</em> in order to abort the
      submission.  Valid for:
      <ul>
	<li>Forms only.
      </ul>
  <dt><b>onClick</b>
  <dd>The mouse has clicked on an item in a fill-out form.
      Valid for:
      <ul>
	<li>Buttons (including submit, reset, and image buttons)
	<li>Checkboxes
	<li>Radio buttons
      </ul>
  <dt><b>onChange</b>
  <dd>The user has changed the contents of a field.
      Valid for:
      <ul>
	<li>Text fields
	<li>Text areas
	<li>Password fields
	<li>File fields
	<li>Popup Menus
	<li>Scrolling lists
      </ul>
  <dt><b>onFocus</b>
  <dd>The user has selected a field to work with.  Valid for:
      <ul>
	<li>Text fields
	<li>Text areas
	<li>Password fields
	<li>File fields
	<li>Popup Menus
	<li>Scrolling lists
      </ul>
  <dt><b>onBlur</b>
  <dd>The user has deselected a field (gone to work somewhere
      else).  Valid for:
      <ul>
	<li>Text fields
	<li>Text areas
	<li>Password fields
	<li>File fields
	<li>Popup Menus
	<li>Scrolling lists
      </ul>
  <dt><b>onSelect</b>
  <dd>The user has changed the part of a text field that is
      selected.  Valid for:
      <ul>
	<li>Text fields
	<li>Text areas
	<li>Password fields
	<li>File fields
      </ul>
</dl>
In order to register a JavaScript event handler with an HTML element,
just use the event name as a parameter when you call the
corresponding CGI method.  For example, to have your
<code>validateAge()</code> JavaScript code executed every time the
textfield named "age" changes, generate the field like this:
<pre>
   print $q-&gt;textfield(-name=&gt;'age',-onChange=&gt;"validateAge(this)");
</pre>
This example assumes that you've already declared the
<code>validateAge()</code> function by incorporating it into
a &lt;SCRIPT&gt; block.  The CGI.pm
<a href="#html">start_html()</a> method provides a convenient way
to create this section.
<p>
Similarly, you can create a form that checks itself over for
consistency and alerts the user if some essential value is missing by
creating it this way:
<pre>
   print $q-&gt;startform(-onSubmit=&gt;"validateMe(this)");
</pre>
See the <a href="examples/javascript.cgi">javascript.cgi</a> script for a
demonstration of how this all works.
<p>
<a href="#contents">Table of contents</a>

<hr>
<a name="stylesheets">
<h2>Limited Support for Cascading Style Sheets</h2>
</a>

CGI.pm has limited support for HTML3's cascading style sheets (css).
To incorporate a stylesheet into your document, pass the
<strong>start_html()</strong> method a <strong>-style</strong>
parameter.  The value of this parameter may be a scalar, in which case
it is incorporated directly into a &lt;STYLE&gt; section, or it may be
a hash reference.  In the latter case you should provide the hash with
one or more of <strong>-src</strong> or <strong>-code</strong>.
<strong>-src</strong> points to a URL where an externally-defined
stylesheet can be found.  <strong>-code</strong> points to a scalar
value to be incorporated into a &lt;STYLE&gt; section.  Style
definitions in <strong>-code</strong> override similarly-named ones in
<strong>-src</strong>, hence the name "cascading."

<p>

To refer to a style within the body of your document, add the
<strong>-class</strong> parameter to any HTML element:

<blockquote><pre>
print h1({-class=&gt;'Fancy'},'Welcome to the Party');
</pre></blockquote>

Or define styles on the fly with the <strong>-style</strong> parameter:

<blockquote><pre>
print h1({-style=&gt;'Color: red;'},'Welcome to Hell');
</pre></blockquote>

You may also use the new <strong>span()</strong> element to apply a
style to a section of text:

<blockquote><pre>
print span({-style=&gt;'Color: red;'},
	       h1('Welcome to Hell'),
	       "Where did that handbasket get to?"
          );
</pre></blockquote>

Note that you must import the ":html3" definitions to get the
<strong>span()</strong> and <strong>style()</strong> methods.

<p>

You won't be able to do much with this unless you understand the CSS
specification.  A more intuitive subclassable library for cascading
style sheets in Perl is in the works, but until then, please
read the CSS specification at <a
href="http://www.w3.org/pub/WWW/Style/">http://www.w3.org/pub/WWW/Style/</a>
to find out how to use these features.  Here's a final example to get
you started.

<blockquote><pre>
use CGI qw/:standard :html3/;

#here's a stylesheet incorporated directly into the page
$newStyle=&lt;&lt;END;
&gt;!-- 
    P.Tip {
	margin-right: 50pt;
	margin-left: 50pt;
        color: red;
    }
    P.Alert {
	font-size: 30pt;
        font-family: sans-serif;
      color: red;
    }
--&gt;
END
print header();
print start_html( -title=>'CGI with Style',
                  -style=>{-src=>'http://www.capricorn.com/style/st1.css',
                  -code=>$newStyle}
	         );
print h1('CGI with Style'),
      p({-class=>'Tip'},
        "Better read the cascading style sheet spec before playing with this!"
        ),
      span({-style=>'color: magenta'},"Look Mom, no hands!",
        p(),
        "Whooo wee!"
      );
print end_html;
</pre></blockquote>

<p>
<a href="#contents">Table of contents</a>

<hr>
<A NAME="nph">
<H2>Using NPH Scripts</H2>
</A>

NPH, or "no-parsed-header", scripts bypass the server completely by
sending the complete HTTP header directly to the browser.  This has
slight performance benefits, but is of most use for taking advantage
of HTTP extensions that are not directly supported by your server,
such as server push and PICS headers.

<p>

Servers use a variety of conventions for designating CGI scripts as
NPH.  Many Unix servers look at the beginning of the script's name for
the prefix "nph-".  The Macintosh WebSTAR server and Microsoft's
Internet Information Server, in contrast, try to decide whether a
program is an NPH script by examining the first line of script output.

<p>

CGI.pm supports NPH scripts with a special NPH mode.  When in this
mode, CGI.pm will output the necessary extra header information when
the <code>header()</code> and <code>redirect()</code> methods are
called.

<p>

<strong>Important:</strong> If you use the Microsoft Internet
Information Server, you <em>must</em> designate your script as an NPH
script.  Otherwise many of CGI.pm's features, such as redirection and
the ability to output non-HTML files, will fail.

<p>

There are a number of ways to put CGI.pm into NPH mode:

<dl>
  <dt>In the <strong>use</strong> statement:
  <dd>Simply add ":nph" to the list of symbols to be imported into
      your script:
      <blockquote><pre>
      use CGI qw(:standard :nph)
      </pre></blockquote>
      <p>
  <dt>By calling the <strong>nph()</strong> method:
  <dd>Call <strong>nph()</strong> with a non-zero parameter at any
      point after using CGI.pm in your program.
      <blockquote><pre>
      CGI->nph(1)
      </pre>
      </blockquote>
      <p>
  <dt>By using <strong>-nph</strong> parameters in the
      <strong>header()</strong> and <strong>redirect()</strong>
      statements:
      <blockquote><pre>
      print $q->header(-nph=&gt;1);
      </pre></blockquote>
  <dd>
</dl>

<hr>
<A NAME="advanced">
<H2>Advanced Techniques</H2>
</A>
<H3>A Script that Saves Some Information to a File and Restores It</H3>
This script will save its state to a file of the user's choosing when the
"save" button is pressed, and will restore its state when the "restore" button
is pressed.  Notice that <EM>it's very important to check the file name</EM>
for shell metacharacters so that the script doesn't inadvertently open up a
command or overwrite someone's file.  For this to work, the script's current
directory must be writable by "nobody".
<PRE>
#!/usr/local/bin/perl

use CGI;
$query = new CGI;

print $query-&gt;header;
print $query-&gt;start_html("Save and Restore Example");
print "&lt;H1&gt;Save and Restore Example&lt;/H1&gt;\n";

# Here's where we take action on the previous request
&amp;save_parameters($query)              if $query-&gt;param('action') eq 'save';
$query = &amp;restore_parameters($query)  if $query-&gt;param('action') eq 'restore';

# Here's where we create the form
print $query-&gt;startform;
print "Popup 1: ",$query-&gt;popup_menu('popup1',['eenie','meenie','minie']),"\n";
print "Popup 2: ",$query-&gt;popup_menu('popup2',['et','lux','perpetua']),"\n";
print "&lt;P&gt;";
print "Save/restore state from file: ",$query-&gt;textfield('savefile','state.sav'),"\n";
print "&lt;P&gt;";
print $query-&gt;submit('action','save'),$query-&gt;submit('action','restore');
print $query-&gt;submit('action','usual query');
print $query-&gt;endform;

# Here we print out a bit at the end
print $query-&gt;end_html;

sub save_parameters {
    local($query) = @_;
    local($filename) = &amp;clean_name($query-&gt;param('savefile'));
    if (open(FILE,"&gt;$filename")) {
	$query-&gt;save(FILE);
	close FILE;
	print "&lt;STRONG&gt;State has been saved to file $filename&lt;/STRONG&gt;\n";
    } else {
	print "&lt;STRONG&gt;Error:&lt;/STRONG&gt; couldn't write to file $filename: $!\n";
    }
}

sub restore_parameters {
    local($query) = @_;
    local($filename) = &amp;clean_name($query-&gt;param('savefile'));
    if (open(FILE,$filename)) {
	$query = new CGI(FILE);  # Throw out the old query, replace it with a new one
	close FILE;
	print "&lt;STRONG&gt;State has been restored from file $filename&lt;/STRONG&gt;\n";
    } else {
	print "&lt;STRONG&gt;Error:&lt;/STRONG&gt; couldn't restore file $filename: $!\n";
    }
    return $query;
}


# Very important subroutine -- get rid of all the naughty
# metacharacters from the file name. If there are, we
# complain bitterly and die.
sub clean_name {
   local($name) = @_;
   unless ($name=~/^[\w\._-]+$/) {
      print "&lt;STRONG&gt;$name has naughty characters.  Only ";
      print "alphanumerics are allowed.  You can't use absolute names.&lt;/STRONG&gt;";
      die "Attempt to use naughty characters";
   }
   return $name;
}
</PRE>

If you use the CGI save() and restore() methods a lot, you might be
interested in the Whitehead Genome Center's <cite>Boulderio</cite>
file format.  It's a way of transferring semi-strucured data from the
standard output of one program to the standard input of the next.  It
comes with a simple Perl database that allows you to store and
retrieve records from a DBM or DB_File database, and is compatible
with the format used by save() and restore().  You can get more
information on Boulderio from:

<blockquote><pre>
<a href="http://www.genome.wi.mit.edu/genome_software/other/boulder.html">http://www.genome.wi.mit.edu/genome_software/other/boulder.html</a>
</pre></blockquote>

<H3>A Script that Uses Self-Referencing URLs to Jump to Internal Links</H3>
(Without losing form information).
<P>Many people have experienced problems with internal links on pages that have
forms.  Jumping around within the document causes the state of the form to be
reset.  A partial solution is to use the self_url() method to generate a link
that preserves state information.  This script illustrates how this works.
<PRE>
#!/usr/local/bin/perl

use CGI;
$query = new CGI;

# We generate a regular HTML file containing a very long list
# and a popup menu that does nothing except to show that we
# don't lose the state information.
print $query-&gt;header;
print $query-&gt;start_html("Internal Links Example");
print "&lt;H1&gt;Internal Links Example&lt;/H1&gt;\n";

print "&lt;A NAME=\"start\"&gt;&lt;/A&gt;\n"; # an anchor point at the top

# pick a default starting value;
$query-&gt;param('amenu','FOO1') unless $query-&gt;param('amenu');

print $query-&gt;startform;
print $query-&gt;popup_menu('amenu',[('FOO1'..'FOO9')]);
print $query-&gt;submit,$query-&gt;endform;

# We create a long boring list for the purposes of illustration.
$myself = $query-&gt;self_url;
print "&lt;OL&gt;\n";
for (1..100) {
    print qq{&lt;LI&gt;List item #$_&lt;A HREF="$myself#start"&gt;Jump to top&lt;/A&gt;\n};
}
print "&lt;/OL&gt;\n";

print $query-&gt;end_html;
</PRE>

<H3>Multiple forms on the same page</H3>
There's no particular trick to this.  Just remember to close one form before
you open another one.  You can reuse the same query object or create a new one.
Either technique works.
<P>
There is, however, a problem with maintaining the states of multiple forms.  Because
the browser only sends your script the parameters from the form in which the submit
button was pressed, the state of all the other forms will be lost.  One way to get
around this, suggested in this example, is to use hidden fields to pass as much
information as possible regardless of which form the user submits.
<PRE>
#!/usr/local/bin/perl
use CGI;

$query=new CGI;
print $query-&gt;header;
print $query-&gt;start_html('Multiple forms');
print "&lt;H1&gt;Multiple forms&lt;/H1&gt;\n";

# form 1
print "&lt;HR&gt;\n";
print $query-&gt;startform;
print $query-&gt;textfield('text1'),$query-&gt;submit('submit1');
print $query-&gt;hidden('text2');  # pass information from the other form
print $query-&gt;endform;
print "&lt;HR&gt;\n";

# form 2
print $query-&gt;startform;
print $query-&gt;textfield('text2'),$query-&gt;submit('submit2');
print $query-&gt;hidden('text1');  # pass information from the other form
print $query-&gt;endform;
print "&lt;HR&gt;\n";
print $query-&gt;end_html;
</PRE>
<p>
<A HREF="#contents">Table of contents</A>
<HR>

<h2><a name="mod_perl">Using CGI.pm with mod_perl and FastCGI</a></h2>

<h3>FastCGI</h3>

<a href="http://www.fastcgi.com">FastCGI</a> is a protocol invented by
OpenMarket that markedly speeds up CGI scripts under certain
circumstances.  It works by opening up the script at server startup
time and redirecting the script's IO to a Unix domain socket.  Every
time a new CGI request comes in, the script is passed new parameters
to work on.  This allows the script to perform all its time-consuming
operations at initialization time (including loading CGI.pm!) and then
respond quickly to new requests.

<p>

FastCGI modules are available for the Apache and NCSA servers as well
as for OpenMarket's own server.  In order to use FastCGI with Perl you
have to run a specially-modified version of the Perl interpreter.
Precompiled Binaries and a patch kit are all available on OpenMarket's
FastCGI web site.

<p>

To use FastCGI with CGI.pm, change your scripts as follows:

<h4>Old Script</h4>
<blockquote><pre>
#!/usr/local/bin/perl
use CGI qw(:standard);
print header,
      start_html("CGI Script"),
      h1("CGI Script"),
      "Not much to see here",
      hr,
      address(a({href=>'/'},"home page"),  
      end_html;
</pre></blockquote>

<h4>New Script</h4>
<blockquote><pre>
#!/usr/local/fcgi/bin/perl
use Fast::CGI qw(:standard);

# Do time-consuming initialization up here.
while (new CGI::Fast) {
   print header,
      start_html("CGI Script"),
      h1("CGI Script"),
      "Not much to see here",
      hr,
      address(a({href=>'/'},"home page"),  
      end_html;
}
</pre></blockquote>

That's all there is to it.  The param() method, form-generation, HTML
shortcuts, etc., all work the way you expect.

<h3>mod_perl</h3>

<a href="http://www.perl.com/CPAN/modules/Apache/">mod_perl</a> is a
module for the Apache Web server that embeds a Perl interpreter into
the Web server.  It can be run in either of two modes:

<ol>
  <li>Server launches a new Perl interpreter every time it needs to
      interpret a Perl script.  This speeds CGI scripts significantly
      because there's no overhead for launching a new Perl process.
  <li>A "fast" mode in which the server launches your script at
      initialization time. You can
      load all your favorite modules (like CGI.pm!) at initialization time,
      greatly speeding things up.
</ol>

As of 2.32, CGI.pm works with mod_perl, versions 0.95 and higher
(fingers crossed!).  If you use Perl 5.003_92 or higher, and compiled
it with the sfio (standard IO) library, you probably do not need to
change your scripts at all.  They should run completely unmodified.
This has been tested successfully.

<p>

If you use Perl 5.003_93 or higher, your scripts should also run
unmodified even if you didn't compile with sfio, because mod_perl
takes advantage of the tied filehandle interface present in that
version of Perl.  However <em>this has not been tested</em> (I'm too
lazy to have two versions of the Perl libraries installed).  If you
find that this does not work as advertised, just use the
<cite>CGI::Apache</cite> module as shown below.  This <em>has</em>
been tested:

<h4>Old Script</H4>

<blockquote><pre>
#!/usr/local/bin/perl
use CGI qw(:standard);
print header,
      start_html("CGI Script"),
      h1("CGI Script"),
      "Not much to see here",
      hr,
      address(a({href=>'/'},"home page"),  
      end_html;
</pre></blockquote>

<h4>New Script</h4>
<blockquote><pre>
#!/usr/bin/perl
use CGI::Apache qw(:standard);

print header,
    start_html("CGI Script"),
    h1("CGI Script"),
    "Not much to see here",
    hr,
    address(a({href=>'/'},"home page"),  
    end_html;
}
</pre></blockquote>

<strong>Important configuration note:</strong> When using CGI.pm with
mod_perl be careful <strong>not</strong> to enable either the
<tt>PerlSendHeader</tt> or <tt>PerlSetupEnv</tt> directives.  This is
handled automatically by CGI.pm and by Apache::Registry.

<p>

Users of CGI::Switch can continue to use it to create scripts that can
run under each of normal CGI, mod_perl CGI or the command line.
Unfortunately the "simple" interface to the CGI.pm functions does not
work with CGI::Switch.  You'll have to use the object-oriented
versions (or use the sfio version of Perl!)

<p>
<A HREF="#contents">Table of contents</A>
<HR>

<H2><a name="migrating">Migrating from cgi-lib.pl</a></H2>

To make it easier to convert older scripts that use cgi-lib.pl,
CGI.pm provides a <strong>CGI::ReadParse()</strong> call that
is compatible with cgi-lib.pl's <strong>ReadParse()</strong>
subroutine.
<p>

When you call ReadParse(), CGI.pm creates an associative array
named <code>%in</code> that contains the named CGI
parameters.  Multi-valued parameters are separated by "\0"
characters in exactly the same way cgi-lib.pl does it.  To
port an old script to CGI.pm, you have to make just two changes:

<h4>Old Script</h4>
<pre>
    require "cgi-lib.pl";
    ReadParse();
    print "The price of your purchase is $in{price}.\n";
</pre>

<h4>New Script</h4>
<pre>
    use CGI qw(:cgi-lib);
    ReadParse();
    print "The price of your purchase is $in{price}.\n";
</pre>

Like cgi-lib's ReadParse, pass a variable <em>glob</em> in
order to use a different variable than the default "%in":
<pre>
   ReadParse(*Q);
   @partners = split("\0",$Q{'golf_partners'});
</pre>

<p>
The associative array created by CGI::ReadParse() contains
a special key 'CGI', which returns the CGI query object
itself:
<pre>
    ReadParse();
    $q = $in{CGI};
    print $q-&gt;textfield(-name=&gt;'wow',
                        -value=&gt;'does this really work?');
</pre>
<p>

This allows you to add the more interesting features
of CGI.pm to your old scripts without rewriting them completely.
As an added benefit, the <strong>%in</strong> variable is
actually <code>tie()</code>'d to the CGI object.  Changing the
CGI object using <strong>param()</strong> will dynamically
change <strong>%in</strong>, and vice-versa.

<p>

cgi-lib.pl's <code>@in</code> and <code>$in</code> variables are
<strong>not</strong> supported.  In addition, the extended version of
ReadParse() that allows you to spool uploaded files to disk is not
available.  You are strongly encouraged to use CGI.pm's file upload
interface instead.

<p>

See <a href="cgi-lib_porting.html">cgi-lib_porting.html</a> for more
details on porting cgi-lib.pl scripts to CGI.pm.

<HR>

<H2>
<A NAME=upload_caveats>
Using the File Upload Feature
</A>
</H2>

The file upload feature doesn't work with every combination of browser
and server.  The various versions of Netscape on the Macintosh, Unix
and Windows platforms don't all seem to implement file uploading in
exactly the same way.  I've tried to make CGI.pm work with all
versions on all platforms, but I keep getting reports from people of
instances that break the file upload feature.

<p>

Known problems include:

<ol>
  <li>Large file uploads may fail when using SSL version 2.0.  This
      affects the Netscape servers and possibly others that use the SSL
      library.  I have received reports that WebSite Pro suffers from
      this problem.  This is a documented bug in the
      Netscape implementation of SSL and not a problem with CGI.pm.
  <li>Microsoft IIS version 3.0 truncates file uploads greater than
      57 K, regardless of whether or not you're using SSL.  Version 2.0
      is not affected by this problem.
  <li>If you try to upload a <strong>directory</strong> path with Unix
      Netscape, the browser will hang until you hit the "stop" button.
      I haven't tried to figure this one out since I think it's dumb
      of Netscape to allow this to happen at all.
  <li>If you create the CGI object in one package (e.g. "main") and
      then obtain the filehandle in a different package (e.g. "foo"),
      the filehandle will be accessible through "main" but not "foo".
      In order to use the filehandle, try the following contortion:
      <blockquote><pre>
      $file = $query-&gt;param('file to upload');
      $file = "main::$file";
          ...
      </pre></blockquote>
      I haven't found a way to determine the correct caller in this
      situation.  I might add a readFile() method to CGI if this
      problem bothers enough people.
</ol>

The main technical challenge of handling file uploads is that
it potentially involves sending more data to the CGI script
than the script can hold in main memory.  For this reason
CGI.pm creates temporary files in
either the <CODE>/usr/tmp</CODE> or the <CODE>/tmp</CODE>
directory.  These temporary files
have names like <CODE>CGItemp125421</CODE>, and should be
deleted automatically.
<P>

<H3>Frequent Problems</H3>

<h4>When you run a script from the command line, it says "offline
mode: enter name=value pairs on standard input".  What do I do
now?</h4>
This is a prompt to enter some CGI parameters for the purposes of
debugging.  You can now type in some parameters like this:

<pre>
    first_name=Fred
    last_name=Flintstone
    city=Bedrock
</pre>

End the list by typing a control-D (or control-Z on DOS/Windows
systems).

<p>

If you want to run a CGI script from a script or batch file, and don't
want this behavior, just pass it an empty parameter list like this:

<pre>
     my_script.pl ''
</pre>

This will work too on Unix systems:

<pre>
     my_script.pl &lt;/dev/null
</pre>

<H4>You can't retrieve the name of the uploaded file
using the param() method</H4>
Most likely the remote user isn't using version 2.0 (or higher)
of Netscape.  Alternatively she just isn't filling in the form
completely.

<h4>When you accidentally try to upload a directory name,
the browser hangs</h4>

This seems to be a Netscape browser problem.  It starts to
upload junk to the script, then hangs.  You can abort by
hitting the "stop" button.

<H4>You can read the name of the uploaded file, but can't
retrieve the data</H4>
First check that you've told CGI.pm to
use the new <A HREF="#multipart">multipart/form-data</A>
scheme.  If it still isn't working, there may be a problem
with the temporary files that CGI.pm needs to create in
order to read in the (potentially very large) uploaded files.
Internally, CGI.pm tries to create temporary files with
names similar to <CODE>CGITemp123456</CODE> in a temporary
directory.  To find a suitable directory it first looks
for <CODE>/usr/tmp</CODE> and then for <CODE>/tmp</CODE>.
If it can't find either of these directories, it tries
for the current directory, which is usually the same
directory that the script resides in.  

<P>

If you're on a non-Unix system you may need to modify
CGI.pm to point at a suitable temporary directory. This
directory must be
writable by the user ID under which the server runs (usually
"nobody") and must have sufficient capacity to handle large
file uploads.  Open up CGI.pm, and find the line:
<PRE>
      package TempFile;
      foreach ('/usr/tmp','/tmp') {
         do {$TMPDIRECTORY = $_; last} if -w $_;
      }
</PRE>
Modify the foreach() line to contain a series of one or more
directories to store temporary files in.

<h4>On Windows Systems, the temporary file is never deleted, but hangs
around in <code>\temp</code>, taking up space.</h4>

Be sure to close the filehandle before your program exits.  

<h4>When you press the "back" button, the same page is loaded,
not the previous one.</h4>
Netscape 2.0's history list gets confused when processing multipart
forms.  If the script generates different pages for the form and the
results, hitting the "back" button doesn't always return you to the
previous page; instead Netscape reloads the current page.  This happens
even if you don't use an upload file field in your form.

<p>

A workaround for this is to use additional path information to trick
Netscape into thinking that the form and the response have different
URLs.  I recommend giving each form a sequence number and bumping the
sequence up by one each time the form is accessed:

<pre>
   my($s) = $query-&gt;path_info=~/(\d+)/; # get sequence
   $s++;                                #bump it up
   # Trick Netscape into thinking it's loading a new script:
   print $q-&gt;start_multipart_form(-action=&gt;$q-&gt;script_name . '/$s');
</pre>

<h4>You can't find the temporary file that CGI.pm creates</h4>
You're encouraged to copy the data into your own file by reading from the
file handle that CGI.pm provides you with.  In the future there
may be no temporary file at all, just a pipe.  However, for now, if
you really want to get at the temp file, you can retrieve its path
using the <a href="#tmpfilename">tmpFileName()</a> method.  Be sure
to move the temporary file elsewhere in the file system if you don't
want it to be automatically deleted when CGI.pm exits.
<HR>

<H3><A NAME="non_unix">Using CGI.pm on non-Unix Platforms</A></H3>

I don't have access to all the combinations of hardware and software
that I really need to make sure that CGI.pm works consistently for all
Web servers, so I rely heavily on helpful reports from users like
yourself.

<p>

There are a number of differences in file name and text processing
conventions on different platforms.  By default, CGI.pm is set up to
work properly on a Unix (or Linux) system.  During load, it will
attempt to guess the correct operating system using the Config module.
Currently it guesses correctly; however if the operating system names
change it may not work right.  The main symptom will be that file
upload does not work correctly.  If this happens, find the place at
the top of the script where the OS is defined, and uncomment the
correct definition:

<pre>
   # CHANGE THIS VARIABLE FOR YOUR OPERATING SYSTEM
   # $OS = 'UNIX';
   # $OS = 'MACINTOSH';
   # $OS = 'WINDOWS';
   # $OS = 'VMS';
</pre>

Other notes follow:

<H4>Windows NT</H4>

CGI.pm works well with WebSite, the EMWACS server, Purveyor and the
Microsoft IIS server.  CGI.pm must be put in the perl5 library
directory, and all CGI scripts that use it should be placed in cgi-bin
directory.  You also need to associate the <CODE>.pl</CODE> suffix
with perl5 using the NT file manager (Website, Purveyor), or install
the Perl DLL library (IIS).  The home site for the NT port of Perl is:

<blockquote>
<a href="http://www.perl.hip.com/">http://www.perl.hip.com/</a>
</blockquote>

<p>

The Microsoft IIS server is seriously broken with respect to
the handling of <a href="#path_info">additional path information</a>.
If you use the DLL version of Perl, IIS will attempt to execute the
additional path information as a script.  If you use the normal
version of Perl, the additional path information will contain
incorrect information.  This is not a bug in CGI.pm.

<p>

WebSite uses a slightly different cgi-bin directory structure than
the standard.  For this server, place the scripts in the
<CODE>cgi-shl</CODE> directory.  CGI.pm appears to work correctly
in both the Windows95 and WindowsNT versions of WebSite.

<p>

Old Netscape Communications Server technical notes recommended
placing <code>perl.exe</code> in cgi-bin.  This a very bad idea because
it opens up a gaping security hole.  Put a C <code>.exe</code> wrapper
around the perl script until such time as Netscape recognizes NT file
manager associations, or provides a Perl-compatible DLL library for its
servers.

<p>

If you find that binary files get slightly larger when uploaded but
that text files remain the same, then binary made is not correctly
activated.  Be sure to set the $OS variable to 'NT' or 'WINDOWS'.  If
you continue to have problems, make sure you're calling
<strong>binmode()</strong> on the filehandle that you use to write
the uploaded file to disk.

<H4>VMS</H4>

I don't have access to a VMS machine, and I'm not sure whether file upload
works correctly.  Other features are known to work.

<H4>Macintosh</H4>

Most CGI.pm features work with MacPerl version 5.0.6r1 or higher under
the WebStar and MacHTTP servers.  In order to install a Perl program
to use with the Web, you'll need Matthias Nuuracher's PCGI extension,
available at:

<blockquote><pre>
<a href="ftp://err.ethz.ch/pub/neeri/MacPerl/">ftp://err.ethz.ch/pub/neeri/MacPerl/</a>
</pre></blockquote>

Known incompatibilities between CGI.pm and MacPerl include:

<ol>
  <li>The perl compiler will object to the use of -values in named
      parameters.  Put single quotes around this parameter ('-values')
      or use the singular form ('-value') instead.
  <li>File upload isn't working in my hands (Perl goes into an endless
      loop).  Other people have gotten it to work.
</ol>

<HR>

<A NAME="future">
<H2>The Relation of this Library to the CGI Modules</H2>
</A>

This library is maintained in parallel with the full featured CGI,
URL, and HTML modules.  I use this library to test out new ideas
before incorporating them into the CGI hierarchy.  I am continuing to
maintain and improve this library in order to satisfy people who are
looking for an easy-to-use introduction to the world of CGI scripting.

<p>

The CGI::* modules are being reworked to be interoperable with the
excellent LWP modules.  Stay tuned.


<P>The current version of CGI.pm can be found at:
<PRE>  <A HREF="http://www-genome.wi.mit.edu/ftp/pub/software/WWW">
http://www-genome.wi.mit.edu/ftp/pub/software/WWW/</A>
</PRE>
<P>
You are encouraged to look at these other Web-related modules:
<DL>
  <DT> <A HREF="ftp://ftp.acoates.com/acoates/perl/">HTML.pm</A>
  <DD> A module that simplifies the creation of HTML documents
       programatically.

  <DT> <A HREF="http://www-genome.wi.mit.edu/ftp/pub/software/WWW/CGIperl/">
       CGI::Base,CGI::Form,CGI::MiniSrv,CGI::Request and CGI::URI::URL</A>
  <DD> Modules for parsing script input, manipulating URLs, creating
       forms and even launching a miniature Web server.

  <DT> <A HREF="http://www.ics.uci.edu/pub/websoft/libwww-perl/">
       libwww-perl</A>
  <DD> Modules for fetching Web resources from within Perl, writing
       Web robots, and much more.
</DL>
You might also be interested in two packages for creating graphics
on the fly:
<DL>
  <DT> <A HREF="http://www.genome.wi.mit.edu/ftp/pub/software/WWW/GD.html">GD.html</A>
  <DD> A module for creating GIF images on the fly, using Tom Boutell's
       <A HREF="http://www.boutell.com/gd/">gd</A> graphics library.
  <DT> <A HREF="http://www.genome.wi.mit.edu/ftp/pub/software/utilities/">qd.pl</A>
  <DD> A library for creating Macintosh PICT files on the fly (which
       can be converted to GIF or JPEG using NetPBM).
</DL>
<P>
For a collection of CGI scripts of various levels of complexity,
see the companion pages for my book
<A HREF="http://www.genome.wi.mit.edu/WWW/">How to Set Up and
Maintain a World Wide Web Site</A>

<HR> <A NAME="distribution"> <H2>Distribution Information:</H2> </A>
This code is copyright 1995-1997 by Lincoln Stein.  It may be used and
modified freely, but I do request that this copyright notice remain
attached to the file.  You may modify this module as you wish, but if
you redistribute a modified version, please attach a note listing the
modifications you have made.

<HR>
<A NAME="mailingList">
<H2>The CGI-perl mailing list</H2>
</A>

The CGI Perl mailing list is defunct and is unlikely to be
resurrected.  Please address your questions to comp.lang.perl.modules
and to comp.lang.perl.misc.

<H3>Bug Reports</H3>
Address bug reports and comments to:<BR>
<A HREF="mailto:lstein@genome.wi.mit.edu">lstein@genome.wi.mit.edu</A>
<P><A HREF="#contents">Up to table of contents</A>

<HR>

<H2><A NAME="new">Revision History</A></H2>
<h3>Version 2.36</h3>
<ol>
  <li>Expanded JavaScript functionality
  <li>Preliminary support for cascading stylesheets
  <li>Security fixes for file uploads:
      <ul>
	<li>Module will bail out if its temporary file already exists
	<li>Temporary files can now be made completely private to
	    avoid peeking by other users or CGI scripts.
      </ul>
  <li><cite>use CGI qw/:nph/</cite> wasn't working correctly.  Now it
      is.
  <li>Cookie and HTTP date formats didn't meet spec.  Thanks to Mark
      Fisher (fisherm@indy.tce.com) for catching and fixing this.
</ol>

<h3>Version 2.35</h3>
<ol>
  <li>Robustified multipart file upload against incorrect syntax in POST.
  <li>Fixed more problems with mod_perl.
  <li>Added -noScript parameter to start_html().
  <li>Documentation fixes.
</ol>

<h3>Version 2.34</h3>
<ol>
  <li>Stupid typo fix
</ol>

<h3>Version 2.33</h3>
<ol>
  <li>Fixed a warning about an undefined environment variable.
  <li>Doug's patch for redirect() under mod_perl
  <li>Partial fix for busted inheritence from CGI::Apache
  <li>Documentation fixes.
</ol>

<h3>Version 2.32</h3>
<ol>
  <li>Improved support for Apache's mod_perl.
  <li>Changes to better support inheritance.
  <li>Support for OS/2.
</ol>

<h3>Version 2.31</h3>
<ol>
  <li>New <strong>uploadInfo()</strong> method to obtain header
      information from uploaded files.
  <li><strong>cookie()</strong> without any arguments returns all the
      cookies passed to a script.
  <li>Removed annoying warnings about $ENV{NPH} when running with the
      -w switch.
  <li>Removed operator overloading throughout to make compatible with
      new versions of perl.
  <li><strong>-expires</strong> now implies the <strong>-date</strong>
      header, to avoid clock skew.
  <li>WebSite passes cookies in $ENV{COOKIE} rather than $ENV{HTTP_COOKIE}.
      We now handle this, even though it's O'Reilly's fault.
  <li>Tested successfully against new sfio I/O layer.
  <li>Documentation fixes.
</ol>

<h3>Version 2.30</h3>
<ol>
  <li>Automatic detection of operating system at load time.
  <li>Changed select() function to Select() in order to avoid
      conflict with Perl built-in.
  <li>Added Tr() as an alternative to TR(); some people think it
      looks better that way.
  <li>Fixed problem with autoloading of MultipartBuffer::DESTROY code.
  <li>Added the following methods:
      <ul>
	<li>virtual_host()
	<li>server_software()
      </ul>
  <li>Automatic NPH mode when running under Microsoft IIS server.
</ol>

<h3>Version 2.29</h3>
<ol>
  <li>Fixed cookie bugs
  <li>Fixed problems that cropped up when useNamedParameters was set to 1.
  <li>Prevent CGI::Carp::fatalsToBrowser() from crapping out when
      encountering a die() within an eval().
  <li>Fixed problems with filehandle initializers.
</ol>

<h3>Version 2.28</h3>
<ol>
  <li>Added support for NPH scripts; also fixes problems with
      Microsoft IIS.
  <li>Fixed a problem with checkbox() values not being correctly saved
      and restored.
  <li>Fixed a bug in which CGI objects created with empty string
      initializers took on default values from earlier CGI objects.
  <li>Documentation fixes.
</ol>

<h3>Version 2.27</h3>
<ol>
  <li>Small but important bug fix: the automatic capitalization of
      tag attributes was accidentally capitalizing the VALUES as
      well as the ATTRIBUTE names (oops).
</ol>

<h3>Version 2.26</h3>
<ol>
  <li>Changed behavior of scrolling_list(), checkbox() and checkbox_group()
      methods so that defaults are honored correctly.  The "fix" causes
      endform() to generate additional &lt;INPUT TYPE="HIDDEN"&gt; tags --
      don't be surpised.
  <li>Fixed bug involving the detection of the SSL protocol.
  <li>Fixed documentation error in position of the -meta argument in start_html().
  <li>HTML shortcuts now generate tags in ALL UPPERCASE.
  <li>start_html() now generates correct SGML header:
      <pre>
      &lt;!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN"&gt;
      </pre>
  <li>CGI::Carp no longer fails "use strict refs" pragma.
</ol>

<h3>Version 2.25</h3>
<ol>
  <li>Fixed bug that caused bad redirection on destination URLs with arguments.
  <li>Fixed bug involving use_named_parameters() followed by start_multipart_form()
  <li>Fixed bug that caused incorrect determination of binmode for Macintosh.
  <li>Spelling fixes on documentation.
</ol>

<H3>Version 2.24</H3>
<ol>
  <li>Fixed bug that caused generation of lousy HTML for some form elements
  <li>Fixed uploading bug in Windows NT
  <li>Some code cleanup (not enough)
</ol>

<H3>Version 2.23</H3>
<ol>
  <li>Fixed an obscure bug that caused scripts to fail mysteriously.
  <li>Fixed auto-caching bug.
  <li>Fixed bug that prevented HTML shortcuts from passing taint checks.
  <li>Fixed some -w warning problems.
</ol>

<H3>Version 2.22</H3>
<ol>
  <li>New CGI::Fast module for use with FastCGI protocol.  See pod
      documentation for details.
  <li>Fixed problems with inheritance and autoloading.
  <li>Added TR() (&lt;tr&gt;) and PARAM() (&lt;param&gt;) methods to
      list of exported HTML tag-generating functions.
  <li>Moved all CGI-related I/O to a bottleneck method so that this can
      be overridden more easily in mod_perl (thanks to Doug MacEachern).
  <li>put() method as substitute for print() for use in mod_perl.
  <li>Fixed crash in tmpFileName() method.
  <li>Added tmpFileName(), startform() and endform() to export list.
  <li>Fixed problems with attributes in HTML shortcuts.
  <li>Functions that don't actually need access to the CGI object now
      no longer generate a default one.  May speed things up slightly.
  <li>Aesthetic improvements in generated HTML.
  <li>New examples.
</ol>

<H3>Version 2.21</H3>
<ol>
  <li>Added the <cite>-meta</cite> argument to <cite>start_html()</cite>.
  <li>Fixed hidden fields (again).
  <li>Radio_group() and checkbox_group() now return an appropriate scalar
      value when called in a scalar context, rather than returning a numeric
      value!
  <li>Cleaned up the formatting of form elements to avoid unesthetic
      extra spaces within the attributes.
  <li>HTML elements now correctly include the closing tag when parameters
      are present but null: em('')
  <li>Added password_field() to the export list.
</ol>

<H3>Version 2.20</H3>
<ol>
  <li>Dumped the SelfLoader because of problems with running with
      taint checks and rolled my own.  Performance is now
      significantly improved.
  <li>Added HTML shortcuts.
  <li><cite>import()</cite> now adheres to the Perl module
      conventions, allowing CGI.pm to import any or all method names
      into the user's name space.
  <li>Added the ability to initialize CGI objects from strings and
      associative arrays.
  <li>Made it possible to initialize CGI objects with filehandle
      references rather than filehandle strings.
  <li>Added the delete_all() and append() methods.
  <li>CGI objects correctly initialize from filehandles on NT/95
      systems now.
  <li>Fixed the problem with binary file uploads on NT/95 systems.
  <li>Fixed bug in redirect().
  <li>Added '-Window-target' parameter to redirect().
  <li>Fixed import_names() so that parameter names containing funny
      characters work.
  <li>Broke the unfortunate connection between cookie and CGI parameter name space.
  <li>Fixed problems with hidden fields whose values are 0.
  <li>Cleaned up the documentation somewhat.
</ol>
<H3>Version 2.19</H3>
<ol>
  <li>Added cookie() support routines.
  <li>Added -expires parameter to header().
  <li>Added cgi-lib.pl compatability mode.
  <li>Made the module more configurable for different
      operating systems.
  <li>Fixed a dumb bug in JavaScript button() method.
</ol>
<H3>Version 2.18</H3>
<ol>
  <li>Fixed a bug that corrects a hang that
      occurs on some platforms when processing file uploads.
      Unfortunately this disables the check for bad Netscape
      uploads.
  <li>Fixed bizarre problem involving the inability to process
      uploaded files that begin with a non alphabetic character
      in the file name.
  <li>Fixed a bug in the hidden fields involving the -override
      directive being ignored when scalar defaults were passed.
  <li>Added documentation on how to disable the SelfLoader features.
</ol>
<H3>Version 2.17</H3>
<ol>
  <li>Added support for the SelfLoader module.
  <li>Added oodles of JavaScript support routines.
  <li>Fixed bad bug in query_string() method that caused some parameters
      to be silently dropped.
  <li>Robustified file upload code to handle premature termination by the
      client.
  <li>Exported temporary file names on file upload.
  <li>Removed spurious "uninitialized variable" warnings that
      appeared when running under 5.002.
  <li>Added the Carp.pm library to the standard distribution.
  <li>Fixed a number of errors in this documentation, and probably
      added a few more.
  <li>Checkbox_group() and radio_group() now return the buttons as arrays,
      so that you can incorporate the individual buttons into specialized
      tables.
  <li>Added the '-nolabels' option to checkbox_group() and radio_group().
      Probably should be added to all the other HTML-generating routines.
  <li>Added the url() method to recover the URL without the entire
      query string appended.
  <li>Added request_method() to list of environment variables available.
  <li>Would you believe it?  Fixed hidden fields <em>again</em>!
</ol>
<H3>Version 2.16</H3>
<ol>
  <li> Fixed hidden fields <em>yet again</em>.
  <li> Fixed subtle problems in the file upload method that caused
      intermittent failures (thanks to Keven Hendrick for this one).
  <li> Made file upload more robust in the face of bizarre behavior
      by the Macintosh and Windows Netscape clients.
  <li> Moved the POD documentation to the bottom of the module
      at the request of Stephen Dahmen.
  <li> Added the -xbase parameter to the start_html() method, also
      at the request of Stephen Dahmen.
  <li> Added JavaScript form buttons at Stephen's request.  I'm not sure how to
      use this Netscape extension correctly, however, so for now the form()
      method is in the module as an undocumented feature.
      Use at your own risk!
</ol>
<H3>Version 2.15</H3>
<OL>
  <LI> Added the <B>-override</B> parameter to all field-generating
       methods.
  <LI> Documented the <CODE>user_name()</CODE> and <CODE>remote_user()</CODE>
       methods.
  <LI> Fixed bugs that prevented empty strings from being recognized
       as valid textfield contents.
  <li> Documented the use of framesets and added a frameset example.
</OL>
<h3>Version 2.14</h3>
This was an internal experimental version that was never released.
<H3>Version 2.13</H3>
<OL>
  <LI>Fixed a bug that interfered with the value "0" being entered into
       text fields.
</OL>
<H3>Version 2.01</H3>
<OL>
  <LI>Added -rows and -columns to the radio and checkbox groups.
       No doubt this will cause much grief because it seems to
       promise a level of meta-organization that it doesn't
       actually provide.
  <LI>Fixed a bug in the redirect() method -- it was not truly
       HTTP/1.0 compliant.
</OL>

<H3>Version 2.0</H3>
The changes seemed to touch every line of code, so I decided
to bump up the major version number.
<OL>
  <LI> Support for <A HREF="#named_param">named parameter
       style method calls.</A>  This turns out to be a
       big win for extending CGI.pm when Netscape adds
       new HTML "features".
  <LI> Changed behavior of hidden fields back to the correct
       "sticky" behavior.
       <A HREF="#hidden_fields_warning">This is going to
       break some programs,</A> but it is for the best in
       the long run.
  <LI> Netscape 2.0b2 broke the file upload feature.  CGI.pm now
       handles both 2.0b1 and 2.0b2-style uploading.  It will
       probably break again in 2.0b3.
  <LI> There were still problems with library being unable to
       distinguish between a form being loaded for the first time,
       and a subsequent loading with all fields blank.  We now
       forcibly create a default name for the Submit button (if not
       provided) so that there's always at least one parameter.
  <LI> More workarounds to prevent annoying spurious warning messages
       when run under the -w switch.  -w is seriously broken in
       perl 5.001!
</OL>

<H3>Version 1.57</H3>
<OL>
  <LI> Support for the Netscape 2.0 "File upload" field.
  <LI> The handling of defaults for selected items in scrolling lists
       and multiple checkboxes is now consistent.
</OL>
<H3>Version 1.56</H3>
<OL>
  <LI> Created true "pod" documentation for the module.
  <LI> Cleaned up the code to avoid many of the spurious
       "use of uninitialized variable" warnings when running
       with the -w switch.
  <LI> Added the <CODE>autoEscape()</CODE> method.
  <LI> Added string interpolation of the CGI object.
  <LI> Added the ability to pass additional parameters to
       the &lt;BODY&gt; tag.
  <LI> Added the ability to specify the status code in the
       HTTP header.
</OL>

<H3>Bug fixes in version 1.55</H3>
<OL>
  <LI> Every time self_url() was called, the parameter list
       would grow.  This was a bad "feature".
  <LI> Documented the fact that you can pass "-" to
       radio_group() in order to prevent any button from
       being highlighted by default.
</OL>
<H3>Bug fixes in version 1.54</H3>
<OL>
  <LI> The user_agent() method is now documented;
  <LI> A potential security hole in import() is now plugged.
  <LI> Changed name of import() to import_names() for compatability
       with CGI:: modules.
</OL>
<H3>Bug fixes in version 1.53</H3>
<OL>
  <LI> Fixed several typos in the code that were causing the following
       subroutines to fail in some circumstances
       <OL>
	 <LI> checkbox()
	 <LI> hidden()
       </OL>
  <LI> No features added
</OL>
<H3>New features added in version 1.52</H3>
<OL>
  <LI> Added backslashing, quotation marks, and other shell-style
       escape sequences to the parameters passed in during debugging
       off-line.
  <LI> Changed the way that the hidden() method works so that the
       default value always overrides the current one.
  <LI> Improved the handling of sticky values in forms.  It's now less
       likely that sticky values will get stuck.
  <LI> If you call server_name(), script_name() and several other
       methods when running offline, the methods now create "dummy"
       values to work with.
</OL>
<H3>Bugs fixed in version 1.51</H3>
<OL>
  <LI> param() when called without arguments was returning an array of
       length 1 even when there were no parameters to be had.  Bad bug!
       Bad!
  <LI> The HTML code generated would break if input fields contained
       the forbidden characters &quot;&gt;&lt; or &amp;.  You can now use these characters
       freely.
</OL>
<H3>New features added in version 1.50</H3>
<OL>
  <LI> import() method allows all the parameters to be
       imported into a namespace in one fell swoop.
  <LI> Parameters are now returned in the same order in which they
       were defined.
</OL>
<H3>Bugs fixed in version 1.45</H3>
<OL>
  <LI> delete() method didn't work correctly.  This is now fixed.
  <LI> reset() method didn't allow you to set the name of the button.  Fixed.
</OL>
<H3>Bugs fixed in version 1.44</H3>
<OL>
  <LI>self_url() didn't include the path information.  This is now
       fixed.
</OL>
<H3>New features added in version 1.43</H3>
<OL>
  <LI>Added the delete() method.
</OL>
<H3>New features added in version 1.42</H3>
<OL>
  <LI>The image_button() method to create clickable images.
  <LI>A few bug fixes involving forms embedded in &lt;PRE&gt; blocks.
</OL>
<H3>New features added in version 1.4</H3>
<OL>
<LI>New header shortcut methods
     <UL>
       <LI>redirect() to create HTTP redirection messages.
       <LI>start_html() to create the HTML title, complete with
	    the recommended &lt;LINK&gt; tag that no one ever remembers
            to include.
       <LI>end_html() for completeness' sake.
     </UL>

<LI>A new save() method that allows you to write out the state of an
     script to a file or pipe.

<LI>An improved version of the new() method that allows you to restore the
     state of a script from a file or pipe.  With (2) this gives
     you dump and restore capabilities!  (Wow, you can put a
     "121,931 customers served" banner at the bottom of your pages!)

<LI> A self_url() method that allows you to create state-maintaining
     hypertext links.  In addition to allowing you to maintain the
     state of your scripts between invocations, this lets you work
     around a problem that some browsers have when jumping to
     internal links in a document that contains a form -- the form 
     information gets lost.

<LI>The user-visible labels in checkboxes, radio buttons, popup menus
     and scrolling lists have now been decoupled from the values
     sent to your CGI script.  Your script can know a checkbox
     by the name of "cb1" while the user knows it by a more
     descriptive name. I've also added some parameters that were
     missing from the text fields, such as MAXLENGTH.

<LI>A whole bunch of methods have been added to get at environment
     variables involved in user verification and other obscure
     features.
</OL>

<H3>Bug fixes</H3>
<OL>
  <LI>The problems with the hidden fields have (I hope at last) been
       fixed.

  <LI>You can create multiple query objects and they will all be
       initialized correctly.  This simplifies the creation of
       multiple forms on one page.

  <LI>The URL unescaping code works correctly now.
</OL>
<A HREF="#contents">Table of Contents</A>
<HR>
<ADDRESS>Lincoln D. Stein, lstein@genome.wi.mit.edu<br>
<a href="/">Whitehead Institute/MIT Center for Genome Research</a></ADDRESS>
<P>
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Last modified: Fri May  9 11:28:36 EDT 1997
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