"there lived a minotaur named",
      strong("Fred."),
      ),
      hr;

=head2 Providing arguments to HTML shortcuts

The HTML methods will accept zero, one or multiple arguments.  If you
provide no arguments, you get a single tag:

   print hr;  	#  <hr>

If you provide one or more string arguments, they are concatenated
together with spaces and placed between opening and closing tags:

   print h1("Chapter","1"); # <h1>Chapter 1</h1>"

If the first argument is a hash reference, then the keys
and values of the hash become the HTML tag's attributes:

   print a({-href=>'fred.html',-target=>'_new'},
      "Open a new frame");

	    <a href="fred.html",target="_new">Open a new frame</a>

You may dispense with the dashes in front of the attribute names if
you prefer:

   print img {src=>'fred.gif',align=>'LEFT'};

	   <img align="LEFT" src="fred.gif">

Sometimes an HTML tag attribute has no argument.  For example, ordered
lists can be marked as COMPACT.  The syntax for this is an argument that
that points to an undef string:

   print ol({compact=>undef},li('one'),li('two'),li('three'));

Prior to CGI.pm version 2.41, providing an empty ('') string as an
attribute argument was the same as providing undef.  However, this has
changed in order to accommodate those who want to create tags of the form 
<img alt="">.  The difference is shown in these two pieces of code:

   CODE                   RESULT
   img({alt=>undef})      <img alt>
   img({alt=>''})         <img alt="">

=head2 The distributive property of HTML shortcuts

One of the cool features of the HTML shortcuts is that they are
distributive.  If you give them an argument consisting of a
B<reference> to a list, the tag will be distributed across each
element of the list.  For example, here's one way to make an ordered
list:

   print ul(
             li({-type=>'disc'},['Sneezy','Doc','Sleepy','Happy'])
           );

This example will result in HTML output that looks like this:

   <ul>
     <li type="disc">Sneezy</li>
     <li type="disc">Doc</li>
     <li type="disc">Sleepy</li>
     <li type="disc">Happy</li>
   </ul>

This is extremely useful for creating tables.  For example:

   print table({-border=>undef},
           caption('When Should You Eat Your Vegetables?'),
           Tr({-align=>'CENTER',-valign=>'TOP'},
           [
              th(['Vegetable', 'Breakfast','Lunch','Dinner']),
              td(['Tomatoes' , 'no', 'yes', 'yes']),
              td(['Broccoli' , 'no', 'no',  'yes']),
              td(['Onions'   , 'yes','yes', 'yes'])
           ]
           )
        );

=head2 HTML shortcuts and list interpolation

Consider this bit of code:

   print blockquote(em('Hi'),'mom!'));

It will ordinarily return the string that you probably expect, namely:

   <blockquote><em>Hi</em> mom!</blockquote>

Note the space between the element "Hi" and the element "mom!".
CGI.pm puts the extra space there using array interpolation, which is
controlled by the magic $" variable.  Sometimes this extra space is
not what you want, for example, when you are trying to align a series
of images.  In this case, you can simply change the value of $" to an
empty string.

   {
      local($") = '';
      print blockquote(em('Hi'),'mom!'));
    }

I suggest you put the code in a block as shown here.  Otherwise the
change to $" will affect all subsequent code until you explicitly
reset it.

=head2 Non-standard HTML shortcuts

A few HTML tags don't follow the standard pattern for various
reasons.  

B<comment()> generates an HTML comment (<!-- comment -->).  Call it
like

    print comment('here is my comment');

Because of conflicts with built-in perl functions, the following functions
begin with initial caps:

    Select
    Tr
    Link
    Delete
    Accept
    Sub

In addition, start_html(), end_html(), start_form(), end_form(),
start_multipart_form() and all the fill-out form tags are special.
See their respective sections.

=head2 Autoescaping HTML

By default, all HTML that is emitted by the form-generating functions
is passed through a function called escapeHTML():

=over 4

=item $escaped_string = escapeHTML("unescaped string");

Escape HTML formatting characters in a string. Internally this calls
L<HTML::Entities> (encode_entities) so really you should just use that
instead - the default list of chars that will be encoded (passed to the
HTML::Entities encode_entities method) is:

    & < > " \x8b \x9b '

you can control this list by setting the value of $CGI::ENCODE_ENTITIES:

    # only encode < >
    $CGI::ENCODE_ENTITIES = q{<>}

if you want to encode B<all> entities then undef $CGI::ENCODE_ENTITIES:

    # encode all entities
    $CGI::ENCODE_ENTITIES = undef;

=back

The automatic escaping does not apply to other shortcuts, such as
h1().  You should call escapeHTML() yourself on untrusted data in
order to protect your pages against nasty tricks that people may enter
into guestbooks, etc..  To change the character set, use charset().
To turn autoescaping off completely, use autoEscape(0):

=over 4

=item $charset = charset([$charset]);

Get or set the current character set.

=item $flag = autoEscape([$flag]);

Get or set the value of the autoescape flag.

=back

=head1 CREATING FILL-OUT FORMS:

I<General note>  The various form-creating methods all return strings
to the caller, containing the tag or tags 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.

I<Another note> The default values that you specify for the forms are only
used the B<first> time the script is invoked (when there is no query
string).  On subsequent invocations of the script (when there is a query
string), the former values are used even if they are blank.  

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

(1) call the param() method to set it.

(2) use the -override (alias -force) parameter (a new feature in version 2.15).
This forces the default value to be used, regardless of the previous value:

   print textfield(-name=>'field_name',
			   -default=>'starting value',
			   -override=>1,
			   -size=>50,
			   -maxlength=>80);

I<Yet another note> By default, the text and labels of form elements are
escaped according to HTML rules.  This means that you can safely use
"<CLICK ME>" as the label for a button.  However, it also interferes with
your ability to incorporate special HTML character sequences, such as &Aacute;,
into your fields.  If you wish to turn off automatic escaping, call the
autoEscape() method with a false value immediately after creating the CGI object:

   $q = CGI->new;
   $q->autoEscape(0);

Note that autoEscape() is exclusively used to effect the behavior of how some
CGI.pm HTML generation functions handle escaping. Calling escapeHTML()
explicitly will always escape the HTML.

I<A Lurking Trap!> Some of the form-element generating methods return
multiple tags.  In a scalar context, the tags will be concatenated
together with spaces, or whatever is the current value of the $"
global.  In a list context, the methods will return a list of
elements, allowing you to modify them if you wish.  Usually you will
not notice this behavior, but beware of this:

    printf("%s\n",end_form())

end_form() produces several tags, and only the first of them will be
printed because the format only expects one value.

<p>


=head2 Creating an isindex tag

   print isindex(-action=>$action);

	 -or-

   print isindex($action);

Prints out an <isindex> tag.  Not very exciting.  The parameter
-action specifies the URL of the script to process the query.  The
default is to process the query with the current script.

=head2 Starting and ending a form

    print start_form(-method=>$method,
		    -action=>$action,
		    -enctype=>$encoding);
      <... various form stuff ...>
    print end_form;

	-or-

    print start_form($method,$action,$encoding);
      <... various form stuff ...>
    print end_form;

start_form() will return a <form> tag with the optional method,
action and form encoding that you specify.  The defaults are:

    method: POST
    action: this script
    enctype: application/x-www-form-urlencoded for non-XHTML
             multipart/form-data for XHTML, see multipart/form-data below.

end_form() returns the closing </form> tag.  

start_form()'s enctype argument tells the browser how to package the various
fields of the form before sending the form to the server.  Two
values are possible:

=over 4

=item B<application/x-www-form-urlencoded>

This is the older type of encoding.  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 B<&CGI::URL_ENCODED>.

=item B<multipart/form-data>

This is the newer type of encoding.
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.  For
your convenience, CGI.pm stores the name of this encoding type
in B<&CGI::MULTIPART>

Forms that use this type of encoding are not easily interpreted
by CGI scripts unless they use CGI.pm or another library designed
to handle them.

If XHTML is activated (the default), then forms will be automatically
created using this type of encoding.

=back

The start_form() method uses the older form of encoding by
default unless XHTML is requested.  If you want to use the
newer form of encoding by default, you can call
B<start_multipart_form()> instead of B<start_form()>.  The
method B<end_multipart_form()> is an alias to B<end_form()>.

JAVASCRIPTING: The B<-name> and B<-onSubmit> parameters are provided
for use with JavaScript.  The -name parameter gives the
form a name so that it can be identified and manipulated by
JavaScript functions.  -onSubmit should point to a JavaScript
function that will be executed just before the form is submitted to your
server.  You can use this opportunity to check the contents of the form 
for consistency and completeness.  If you find something wrong, you
can put up an alert box or maybe fix things up yourself.  You can 
abort the submission by returning false from this function.  

Usually the bulk of JavaScript functions are defined in a <script>
block in the HTML header and -onSubmit points to one of these function
call.  See start_html() for details.

=head2 Form elements

After starting a form, you will typically create one or more
textfields, popup menus, radio groups and other form elements.  Each
of these elements takes a standard set of named arguments.  Some
elements also have optional arguments.  The standard arguments are as
follows:

=over 4

=item B<-name>

The name of the field. After submission this name can be used to
retrieve the field's value using the param() method.

=item B<-value>, B<-values>

The initial value of the field which will be returned to the script
after form submission.  Some form elements, such as text fields, take
a single scalar -value argument. Others, such as popup menus, take a
reference to an array of values. The two arguments are synonyms.

=item B<-tabindex>

A numeric value that sets the order in which the form element receives
focus when the user presses the tab key. Elements with lower values
receive focus first.

=item B<-id>

A string identifier that can be used to identify this element to
JavaScript and DHTML.

=item B<-override>

A boolean, which, if true, forces the element to take on the value
specified by B<-value>, overriding the sticky behavior described
earlier for the B<-nosticky> pragma.

=item B<-onChange>, B<-onFocus>, B<-onBlur>, B<-onMouseOver>, B<-onMouseOut>, B<-onSelect>

These are used to assign JavaScript event handlers. See the
JavaScripting section for more details.

=back

Other common arguments are described in the next section. In addition
to these, all attributes described in the HTML specifications are
supported.

=head2 Creating a text field

    print textfield(-name=>'field_name',
		    -value=>'starting value',
		    -size=>50,
		    -maxlength=>80);
	-or-

    print textfield('field_name','starting value',50,80);

textfield() will return a text input field. 

B<Parameters>

=over 4

=item 1.

The first parameter is the required name for the field (-name). 

=item 2.

The optional second parameter is the default starting value for the field
contents (-value, formerly known as -default).

=item 3.

The optional third parameter is the size of the field in
      characters (-size).

=item 4.

The optional fourth parameter is the maximum number of characters the
      field will accept (-maxlength).

=back

As with all these methods, the field will be initialized with its 
previous contents from earlier invocations of the script.
When the form is processed, the value of the text field can be
retrieved with:

       $value = param('foo');

If you want to reset it from its initial value after the script has been
called once, you can do so like this:

       param('foo',"I'm taking over this value!");

=head2 Creating a big text field

   print textarea(-name=>'foo',
			  -default=>'starting value',
			  -rows=>10,
			  -columns=>50);

	-or

   print textarea('foo','starting value',10,50);

textarea() 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.

=head2 Creating a password field

   print password_field(-name=>'secret',
				-value=>'starting value',
				-size=>50,
				-maxlength=>80);
	-or-

   print password_field('secret','starting value',50,80);

password_field() is identical to textfield(), except that its contents 
will be starred out on the web page.

=head2 Creating a file upload field

    print filefield(-name=>'uploaded_file',
			    -default=>'starting value',
			    -size=>50,
			    -maxlength=>80);
	-or-

    print filefield('uploaded_file','starting value',50,80);

filefield() will return a file upload field.
In order to take full advantage of this I<you must use the new 
multipart encoding scheme> for the form.  You can do this either
by calling B<start_form()> with an encoding type of B<&CGI::MULTIPART>,
or by calling the new method B<start_multipart_form()> instead of
vanilla B<start_form()>.

B<Parameters>

=over 4

=item 1.

The first parameter is the required name for the field (-name).  

=item 2.

The optional second parameter is the starting value for the field contents
to be used as the default file name (-default).

For security reasons, browsers don't pay any attention to this field,
and so the starting value will always be blank.  Worse, the field
loses its "sticky" behavior and forgets its previous contents.  The
starting value field is called for in the HTML specification, however,
and possibly some browser will eventually provide support for it.

=item 3.

The optional third parameter is the size of the field in
characters (-size).

=item 4.

The optional fourth parameter is the maximum number of characters the
field will accept (-maxlength).

=back

JAVASCRIPTING: The B<-onChange>, B<-onFocus>, B<-onBlur>,
B<-onMouseOver>, B<-onMouseOut> and B<-onSelect> parameters are
recognized.  See textfield() for details.

=head2 Creating a popup menu

   print popup_menu('menu_name',
			    ['eenie','meenie','minie'],
			    'meenie');

      -or-

   %labels = ('eenie'=>'your first choice',
	      'meenie'=>'your second choice',
	      'minie'=>'your third choice');
   %attributes = ('eenie'=>{'class'=>'class of first choice'});
   print popup_menu('menu_name',
			    ['eenie','meenie','minie'],
          'meenie',\%labels,\%attributes);

	-or (named parameter style)-

   print popup_menu(-name=>'menu_name',
			    -values=>['eenie','meenie','minie'],
			    -default=>['meenie','minie'],
          -labels=>\%labels,
          -attributes=>\%attributes);

popup_menu() creates a menu. Please note that the -multiple option will be
ignored if passed - use scrolling_list() if you want to create a menu that
supports multiple selections

=over 4

=item 1.

The required first argument is the menu's name (-name).

=item 2.

The required second argument (-values) is an array B<reference>
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 "\@foo".

=item 3.

The optional third parameter (-default) is the name of the default
menu choice.  If not specified, the first item will be the default.
The values of the previous choice will be maintained across
queries. Pass an array reference to select multiple defaults.

=item 4.

The optional fourth parameter (-labels) is provided for people who
want to use different values for the user-visible label inside the
popup menu and the value returned to your script.  It's a pointer to an
hash relating menu values to user-visible labels.  If you
leave this parameter blank, the menu values will be displayed by
default.  (You can also leave a label undefined if you want to).

=item 5.

The optional fifth parameter (-attributes) is provided to assign
any of the common HTML attributes to an individual menu item. It's
a pointer to a hash relating menu values to another
hash with the attribute's name as the key and the
attribute's value as the value.

=back

When the form is processed, the selected value of the popup menu can
be retrieved using:

      $popup_menu_value = param('menu_name');

=head2 Creating an option group

Named parameter style

  print popup_menu(-name=>'menu_name',
                  -values=>[qw/eenie meenie minie/,
                            optgroup(-name=>'optgroup_name',
                                             -values => ['moe','catch'],
                                             -attributes=>{'catch'=>{'class'=>'red'}})],
                  -labels=>{'eenie'=>'one',
                            'meenie'=>'two',
                            'minie'=>'three'},
                  -default=>'meenie');

  Old style
  print popup_menu('menu_name',
                  ['eenie','meenie','minie',
                   optgroup('optgroup_name', ['moe', 'catch'],
                                   {'catch'=>{'class'=>'red'}})],'meenie',
                  {'eenie'=>'one','meenie'=>'two','minie'=>'three'});

optgroup() creates an option group within a popup menu.

=over 4

=item 1.

The required first argument (B<-name>) is the label attribute of the
optgroup and is B<not> inserted in the parameter list of the query.

=item 2.

The required second argument (B<-values>)  is an array reference
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 \@foo.  If you pass a HASH reference,
the keys will be used for the menu values, and the values will be
used for the menu labels (see -labels below).

=item 3.

The optional third parameter (B<-labels>) allows you to pass a reference
to a hash 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).  This is equivalent
to using a hash reference for the -values parameter.

=item 4.

An optional fourth parameter (B<-labeled>) can be set to a true value
and indicates that the values should be used as the label attribute
for each option element within the optgroup.

=item 5.

An optional fifth parameter (-novals) can be set to a true value and
indicates to suppress the val attribute in each option element within
the optgroup.

See the discussion on optgroup at W3C
(http://www.w3.org/TR/REC-html40/interact/forms.html#edef-OPTGROUP)
for details.

=item 6.

An optional sixth parameter (-attributes) is provided to assign
any of the common HTML attributes to an individual menu item. It's
a pointer to a hash relating menu values to another
hash with the attribute's name as the key and the
attribute's value as the value.

=back

=head2 Creating a scrolling list

   print scrolling_list('list_name',
				['eenie','meenie','minie','moe'],
        ['eenie','moe'],5,'true',{'moe'=>{'class'=>'red'}});
      -or-

   print scrolling_list('list_name',
				['eenie','meenie','minie','moe'],
				['eenie','moe'],5,'true',
        \%labels,%attributes);

	-or-

   print scrolling_list(-name=>'list_name',
				-values=>['eenie','meenie','minie','moe'],
				-default=>['eenie','moe'],
				-size=>5,
				-multiple=>'true',
        -labels=>\%labels,
        -attributes=>\%attributes);

scrolling_list() creates a scrolling list.  

B<Parameters:>

=over 4

=item 1.

The first and second arguments are the list name (-name) and values
(-values).  As in the popup menu, the second argument should be an
array reference.

=item 2.

The optional third argument (-default) 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.  In the named
parameter version, you can use the synonym "-defaults" for this
parameter.

=item 3.

The optional fourth argument is the size of the list (-size).

=item 4.

The optional fifth argument can be set to true to allow multiple
simultaneous selections (-multiple).  Otherwise only one selection
will be allowed at a time.

=item 5.

The optional sixth argument is a pointer to a hash
containing long user-visible labels for the list items (-labels).
If not provided, the values will be displayed.

=item 6.

The optional sixth parameter (-attributes) is provided to assign
any of the common HTML attributes to an individual menu item. It's
a pointer to a hash relating menu values to another
hash with the attribute's name as the key and the
attribute's value as the value.

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:

      @selected = param('list_name');

=back

=head2 Creating a group of related checkboxes

   print checkbox_group(-name=>'group_name',
				-values=>['eenie','meenie','minie','moe'],
				-default=>['eenie','moe'],
				-linebreak=>'true',
                                -disabled => ['moe'],
        -labels=>\%labels,
        -attributes=>\%attributes);

   print checkbox_group('group_name',
				['eenie','meenie','minie','moe'],
        ['eenie','moe'],'true',\%labels,
        {'moe'=>{'class'=>'red'}});

   HTML3-COMPATIBLE BROWSERS ONLY:

   print checkbox_group(-name=>'group_name',
				-values=>['eenie','meenie','minie','moe'],
				-rows=2,-columns=>2);


checkbox_group() creates a list of checkboxes that are related
by the same name.

B<Parameters:>

=over 4

=item 1.

The first and second arguments are the checkbox name and values,
respectively (-name and -values).  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.

=item 2.

The optional third argument (-default) 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.

=item 3.

The optional fourth argument (-linebreak) 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.

=back

The optional B<-labels> argument is a pointer to a hash
relating the checkbox values to the user-visible labels that will be
printed next to them.  If not provided, the values will be used as the
default.


The optional parameters B<-rows>, and B<-columns> 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.

The option B<-disabled> takes an array of checkbox values and disables
them by greying them out (this may not be supported by all browsers).

The optional B<-attributes> argument is provided to assign any of the
common HTML attributes to an individual menu item. It's a pointer to
a hash relating menu values to another hash
with the attribute's name as the key and the attribute's value as the
value.

The optional B<-tabindex> argument can be used to control the order in which
radio buttons receive focus when the user presses the tab button.  If
passed a scalar numeric value, the first element in the group will
receive this tab index and subsequent elements will be incremented by
one.  If given a reference to an array of radio button values, then
the indexes will be jiggered so that the order specified in the array
will correspond to the tab order.  You can also pass a reference to a
hash in which the hash keys are the radio button values and the values
are the tab indexes of each button.  Examples:

  -tabindex => 100    #  this group starts at index 100 and counts up
  -tabindex => ['moe','minie','eenie','meenie']  # tab in this order
  -tabindex => {meenie=>100,moe=>101,minie=>102,eenie=>200} # tab in this order

The optional B<-labelattributes> argument will contain attributes
attached to the <label> element that surrounds each button.

When the form is processed, 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:

      @turned_on = param('group_name');

The value returned by checkbox_group() is actually an array of button
elements.  You can capture them and use them within tables, lists,
or in other creative ways:

    @h = checkbox_group(-name=>'group_name',-values=>\@values);
    &use_in_creative_way(@h);

=head2 Creating a standalone checkbox

    print checkbox(-name=>'checkbox_name',
			   -checked=>1,
			   -value=>'ON',
			   -label=>'CLICK ME');

	-or-

    print checkbox('checkbox_name','checked','ON','CLICK ME');

checkbox() is used to create an isolated checkbox that isn't logically
related to any others.

B<Parameters:>

=over 4

=item 1.

The first parameter is the required name for the checkbox (-name).  It
will also be used for the user-readable label printed next to the
checkbox.

=item 2.

The optional second parameter (-checked) specifies that the checkbox
is turned on by default.  Synonyms are -selected and -on.

=item 3.

The optional third parameter (-value) specifies the value of the
checkbox when it is checked.  If not provided, the word "on" is
assumed.

=item 4.

The optional fourth parameter (-label) is the user-readable label to
be attached to the checkbox.  If not provided, the checkbox name is
used.

=back

The value of the checkbox can be retrieved using:

    $turned_on = param('checkbox_name');

=head2 Creating a radio button group

   print radio_group(-name=>'group_name',
			     -values=>['eenie','meenie','minie'],
			     -default=>'meenie',
			     -linebreak=>'true',
           -labels=>\%labels,
           -attributes=>\%attributes);

	-or-

   print radio_group('group_name',['eenie','meenie','minie'],
            'meenie','true',\%labels,\%attributes);


   HTML3-COMPATIBLE BROWSERS ONLY:

   print radio_group(-name=>'group_name',
			     -values=>['eenie','meenie','minie','moe'],
			     -rows=2,-columns=>2);

radio_group() creates a set of logically-related radio buttons
(turning one member of the group on turns the others off)

B<Parameters:>

=over 4

=item 1.

The first argument is the name of the group and is required (-name).

=item 2.

The second argument (-values) is the list of values for the radio
buttons.  The values and the labels that appear on the page are
identical.  Pass an array I<reference> in the second argument, either
using an anonymous array, as shown, or by referencing a named array as
in "\@foo".

=item 3.

The optional third parameter (-default) is the name of the default
button to turn on. If not specified, the first item will be the
default.  You can provide a nonexistent button name, such as "-" to
start up with no buttons selected.

=item 4.

The optional fourth parameter (-linebreak) can be set to 'true' to put
line breaks between the buttons, creating a vertical list.

=item 5.

The optional fifth parameter (-labels) is a pointer to an associative
array relating the radio button values to user-visible labels to be
used in the display.  If not provided, the values themselves are
displayed.

=back

All modern browsers can take advantage of the optional parameters
B<-rows>, and B<-columns>.  These parameters cause radio_group() to
return an HTML3 compatible table containing the radio group 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.

To include row and column headings in the returned table, you
can use the B<-rowheaders> and B<-colheaders> parameters.  Both
of these accept a pointer to an array of headings to use.
The headings are just decorative.  They don't reorganize the
interpretation of the radio buttons -- they're still a single named
unit.

The optional B<-tabindex> argument can be used to control the order in which
radio buttons receive focus when the user presses the tab button.  If
passed a scalar numeric value, the first element in the group will
receive this tab index and subsequent elements will be incremented by
one.  If given a reference to an array of radio button values, then
the indexes will be jiggered so that the order specified in the array
will correspond to the tab order.  You can also pass a reference to a
hash in which the hash keys are the radio button values and the values
are the tab indexes of each button.  Examples:

  -tabindex => 100    #  this group starts at index 100 and counts up
  -tabindex => ['moe','minie','eenie','meenie']  # tab in this order
  -tabindex => {meenie=>100,moe=>101,minie=>102,eenie=>200} # tab in this order


The optional B<-attributes> argument is provided to assign any of the
common HTML attributes to an individual menu item. It's a pointer to
a hash relating menu values to another hash
with the attribute's name as the key and the attribute's value as the
value.

The optional B<-labelattributes> argument will contain attributes
attached to the <label> element that surrounds each button.

When the form is processed, the selected radio button can
be retrieved using:

      $which_radio_button = param('group_name');

The value returned by radio_group() is actually an array of button
elements.  You can capture them and use them within tables, lists,
or in other creative ways:

    @h = radio_group(-name=>'group_name',-values=>\@values);
    &use_in_creative_way(@h);

=head2 Creating a submit button 

   print submit(-name=>'button_name',
			-value=>'value');

	-or-

   print submit('button_name','value');

submit() will create the query submission button.  Every form
should have one of these.

B<Parameters:>

=over 4

=item 1.

The first argument (-name) 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.  

=item 2.

The second argument (-value) is also optional.  This gives the button
a value that will be passed to your script in the query string. The
name will also be used as the user-visible label.

=item 3.

You can use -label as an alias for -value.  I always get confused
about which of -name and -value changes the user-visible label on the
button.

=back

You can figure out which button was pressed by using different
values for each one:

     $which_one = param('button_name');

=head2 Creating a reset button

   print reset

reset() creates the "reset" button.  Note that it restores the
form to its value from the last time the script was called, 
NOT necessarily to the defaults.

Note that this conflicts with the perl reset() built-in.  Use
CORE::reset() to get the original reset function.

=head2 Creating a default button

   print defaults('button_label')

defaults() creates a button that, when invoked, will cause the
form to be completely reset to its defaults, wiping out all the
changes the user ever made.

=head2 Creating a hidden field

	print hidden(-name=>'hidden_name',
			     -default=>['value1','value2'...]);

		-or-

	print hidden('hidden_name','value1','value2'...);

hidden() 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.

B<Parameters:>

=over 4

=item 1.

The first argument is required and specifies the name of this
field (-name).

=item 2.  

The second argument is also required and specifies its value
(-default).  In the named parameter style of calling, you can provide
a single value here or a reference to a whole list

=back

Fetch the value of a hidden field this way:

     $hidden_value = param('hidden_name');

Note, that 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:

     param('hidden_name','new','values','here');

=head2 Creating a clickable image button

     print image_button(-name=>'button_name',
				-src=>'/source/URL',
				-align=>'MIDDLE');      

	-or-

     print image_button('button_name','/source/URL','MIDDLE');

image_button() produces a clickable image.  When it's clicked on the
position of the click is returned to your script as "button_name.x"
and "button_name.y", where "button_name" is the name you've assigned
to it.

B<Parameters:>

=over 4

=item 1.

The first argument (-name) is required and specifies the name of this
field.

=item 2.

The second argument (-src) is also required and specifies the URL

=item 3.

The third option (-align, optional) is an alignment type, and may be
TOP, BOTTOM or MIDDLE

=back

Fetch the value of the button this way:
     $x = param('button_name.x');
     $y = param('button_name.y');

=head2 Creating a javascript action button

     print button(-name=>'button_name',
			  -value=>'user visible label',
			  -onClick=>"do_something()");

	-or-

     print button('button_name',"user visible value","do_something()");

button() produces an C<< <input> >> tag with C<type="button">.  When it's
pressed the fragment of JavaScript code pointed to by the B<-onClick> parameter
will be executed.

=head1 WORKING WITH FRAMES

It's possible for CGI.pm scripts to write into several browser panels
and windows using the HTML 4 frame mechanism.  There are three
techniques for defining new frames programmatically:

=over 4

=item 1. Create a <Frameset> document

After writing out the HTTP header, instead of creating a standard
HTML document using the start_html() call, create a <frameset> 
document that defines the frames on the page.  Specify your script(s)
(with appropriate parameters) as the SRC for each of the frames.

There is no specific support for creating <frameset> sections 
in CGI.pm, but the HTML is very simple to write.  

=item 2. Specify the destination for the document in the HTTP header

You may provide a B<-target> parameter to the header() method:

    print header(-target=>'ResultsWindow');

This will tell the browser to load the output of your script into the
frame named "ResultsWindow".  If a frame of that name doesn't already
exist, the browser will pop up a new window and load your script's
document into that.  There are a number of magic names that you can
use for targets.  See the HTML C<< <frame> >> documentation for details.

=item 3. Specify the destination for the document in the <form> tag

You can specify the frame to load in the FORM tag itself.  With
CGI.pm it looks like this:

    print start_form(-target=>'ResultsWindow');

When your script is reinvoked by the form, its output will be loaded
into the frame named "ResultsWindow".  If one doesn't already exist
a new window will be created.

=back

The script "frameset.cgi" in the examples directory shows one way to
create pages in which the fill-out form and the response live in
side-by-side frames.

=head1 SUPPORT FOR JAVASCRIPT

The usual way to use JavaScript is to define a set of functions in a
<SCRIPT> 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.

The elements that can register event handlers include the <BODY> 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. Here is a
partial list:

=over 4

=item B<onLoad>

The browser is loading the current document. Valid in:

     + The HTML <BODY> section only.

=item B<onUnload>

The browser is closing the current page or frame. Valid for:

     + The HTML <BODY> section only.

=item B<onSubmit>

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 false in order to abort the submission.  Valid for:

     + Forms only.

=item B<onClick>

The mouse has clicked on an item in a fill-out form. Valid for:

     + Buttons (including submit, reset, and image buttons)
     + Checkboxes
     + Radio buttons

=item B<onChange>

The user has changed the contents of a field. Valid for:

     + Text fields
     + Text areas
     + Password fields
     + File fields
     + Popup Menus
     + Scrolling lists

=item B<onFocus>

The user has selected a field to work with. Valid for:

     + Text fields
     + Text areas
     + Password fields
     + File fields
     + Popup Menus
     + Scrolling lists

=item B<onBlur>

The user has deselected a field (gone to work somewhere else).  Valid
for:

     + Text fields
     + Text areas
     + Password fields
     + File fields
     + Popup Menus
     + Scrolling lists

=item B<onSelect>

The user has changed the part of a text field that is selected.  Valid
for:

     + Text fields
     + Text areas
     + Password fields
     + File fields

=item B<onMouseOver>

The mouse has moved over an element.

     + Text fields
     + Text areas
     + Password fields
     + File fields
     + Popup Menus
     + Scrolling lists

=item B<onMouseOut>

The mouse has moved off an element.

     + Text fields
     + Text areas
     + Password fields
     + File fields
     + Popup Menus
     + Scrolling lists

=back

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 validateAge() JavaScript code
executed every time the textfield named "age" changes, generate the
field like this: 

 print textfield(-name=>'age',-onChange=>"validateAge(this)");

This example assumes that you've already declared the validateAge()
function by incorporating it into a <SCRIPT> block. The CGI.pm
start_html() method provides a convenient way to create this section.

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: 
  print start_form(-onSubmit=>"validateMe(this)");

See the javascript.cgi script for a demonstration of how this all
works.


=head1 LIMITED SUPPORT FOR CASCADING STYLE SHEETS

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

You may also specify the type of the stylesheet by adding the optional
B<-type> parameter to the hash pointed to by B<-style>.  If not
specified, the style defaults to 'text/css'.

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

    print h1({-class=>'Fancy'},'Welcome to the Party');

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

    print h1({-style=>'Color: red;'},'Welcome to Hell');

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

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

Note that you must import the ":html3" definitions to have the
B<span()> method available.  Here's a quick and dirty example of using
CSS's.  See the CSS specification at
http://www.w3.org/Style/CSS/ for more information.

    use CGI qw/:standard :html3/;

    #here's a stylesheet incorporated directly into the page
    $newStyle=<<END;
    <!-- 
    P.Tip {
	margin-right: 50pt;
	margin-left: 50pt;
        color: red;
    }
    P.Alert {
	font-size: 30pt;
        font-family: sans-serif;
      color: red;
    }
    -->
    END
    print header();
    print start_html( -title=>'CGI with Style',
		      -style=>{-src=>'http://www.capricorn.com/style/st1.css',
		               -code=>$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;

Pass an array reference to B<-code> or B<-src> in order to incorporate
multiple stylesheets into your document.

Should you wish to incorporate a verbatim stylesheet that includes
arbitrary formatting in the header, you may pass a -verbatim tag to
the -style hash, as follows:

print start_html (-style  =>  {-verbatim => '@import url("/server-common/css/'.$cssFile.'");',
                  -src    =>  '/server-common/css/core.css'});


This will generate an HTML header that contains this:

 <link rel="stylesheet" type="text/css"  href="/server-common/css/core.css">
   <style type="text/css">
   @import url("/server-common/css/main.css");
   </style>

Any additional arguments passed in the -style value will be
incorporated into the <link> tag.  For example:

 start_html(-style=>{-src=>['/styles/print.css','/styles/layout.css'],
			  -media => 'all'});

This will give:

 <link rel="stylesheet" type="text/css" href="/styles/print.css" media="all"/>
 <link rel="stylesheet" type="text/css" href="/styles/layout.css" media="all"/>

<p>

To make more complicated <link> tags, use the Link() function
and pass it to start_html() in the -head argument, as in:

  @h = (Link({-rel=>'stylesheet',-type=>'text/css',-src=>'/ss/ss.css',-media=>'all'}),
        Link({-rel=>'stylesheet',-type=>'text/css',-src=>'/ss/fred.css',-media=>'paper'}));
  print start_html({-head=>\@h})

To create primary and  "alternate" stylesheet, use the B<-alternate> option:

 start_html(-style=>{-src=>[
                           {-src=>'/styles/print.css'},
			   {-src=>'/styles/alt.css',-alternate=>1}
                           ]
		    });

=head2 Dumping out all the name/value pairs

The Dump() 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:

    print Dump

Produces something that looks like:

    <ul>
    <li>name1
	<ul>
	<li>value1
	<li>value2
	</ul>
    <li>name2
	<ul>
	<li>value1
	</ul>
    </ul>

As a shortcut, you can interpolate the entire CGI object into a string
and it will be replaced with the a nice HTML dump shown above:

    $q=CGI->new;
    print "<h2>Current Values</h2> $q\n";


=head1 BUGS

Address bug reports and comments to: L<https://github.com/leejo/CGI.pm/issues>

See the L<https://github.com/leejo/CGI.pm/blob/master/CONTRIBUTING.md> file for information
on raising issues and contributing

The original bug tracker can be found at:
L<https://rt.cpan.org/Public/Dist/Display.html?Queue=CGI.pm>

=head1 SEE ALSO

L<CGI> - The original source of this documentation / functionality

=cut