# phpman > perldoc > perlpod

## NAME
    perlpod - the Plain Old Documentation format

## DESCRIPTION
    Pod is a simple-to-use markup language used for writing documentation for Perl, Perl programs,
    and Perl modules.

    Translators are available for converting Pod to various formats like plain text, HTML, man
    pages, and more.

    Pod markup consists of three basic kinds of paragraphs: ordinary, verbatim, and command.

### Ordinary Paragraph
    Most paragraphs in your documentation will be ordinary blocks of text, like this one. You can
    simply type in your text without any markup whatsoever, and with just a blank line before and
    after. When it gets formatted, it will undergo minimal formatting, like being rewrapped,
    probably put into a proportionally spaced font, and maybe even justified.

    You can use formatting codes in ordinary paragraphs, for bold, *italic*, "code-style",
    hyperlinks, and more. Such codes are explained in the "Formatting Codes" section, below.

### Verbatim Paragraph
    Verbatim paragraphs are usually used for presenting a codeblock or other text which does not
    require any special parsing or formatting, and which shouldn't be wrapped.

    A verbatim paragraph is distinguished by having its first character be a space or a tab. (And
    commonly, all its lines begin with spaces and/or tabs.) It should be reproduced exactly, with
    tabs assumed to be on 8-column boundaries. There are no special formatting codes, so you can't
    italicize or anything like that. A \ means \, and nothing else.

### Command Paragraph
    A command paragraph is used for special treatment of whole chunks of text, usually as headings
    or parts of lists.

    All command paragraphs (which are typically only one line long) start with "=", followed by an
    identifier, followed by arbitrary text that the command can use however it pleases. Currently
    recognized commands are

        =pod
        =head1 Heading Text
        =head2 Heading Text
        =head3 Heading Text
        =head4 Heading Text
        =over indentlevel
        =item stuff
        =back
        =begin format
        =end format
        =for format text...
        =encoding type
        =cut

    To explain them each in detail:

    "=head1 *Heading Text*"
    "=head2 *Heading Text*"
    "=head3 *Heading Text*"
    "=head4 *Heading Text*"
        Head1 through head4 produce headings, head1 being the highest level. The text in the rest of
        this paragraph is the content of the heading. For example:

          =head2 Object Attributes

        The text "Object Attributes" comprises the heading there. The text in these heading commands
        can use formatting codes, as seen here:

          =head2 Possible Values for C<$/>

        Such commands are explained in the "Formatting Codes" section, below.

    "=over *indentlevel*"
    "=item *stuff...*"
    "=back"
        Item, over, and back require a little more explanation: "=over" starts a region specifically
        for the generation of a list using "=item" commands, or for indenting (groups of) normal
        paragraphs. At the end of your list, use "=back" to end it. The *indentlevel* option to
        "=over" indicates how far over to indent, generally in ems (where one em is the width of an
        "M" in the document's base font) or roughly comparable units; if there is no *indentlevel*
        option, it defaults to four. (And some formatters may just ignore whatever *indentlevel* you
        provide.) In the *stuff* in "=item *stuff...*", you may use formatting codes, as seen here:

          =item Using C<$|> to Control Buffering

        Such commands are explained in the "Formatting Codes" section, below.

        Note also that there are some basic rules to using "=over" ... "=back" regions:

        *   Don't use "=item"s outside of an "=over" ... "=back" region.

        *   The first thing after the "=over" command should be an "=item", unless there aren't
            going to be any items at all in this "=over" ... "=back" region.

        *   Don't put "=head*n*" commands inside an "=over" ... "=back" region.

        *   And perhaps most importantly, keep the items consistent: either use "=item *" for all of
            them, to produce bullets; or use "=item 1.", "=item 2.", etc., to produce numbered
            lists; or use "=item foo", "=item bar", etc.--namely, things that look nothing like
            bullets or numbers. (If you have a list that contains both: 1) things that don't look
            like bullets nor numbers, plus 2) things that do, you should preface the bullet- or
            number-like items with "Z<>". See Z<> below for an example.)

            If you start with bullets or numbers, stick with them, as formatters use the first
            "=item" type to decide how to format the list.

    "=cut"
        To end a Pod block, use a blank line, then a line beginning with "=cut", and a blank line
        after it. This lets Perl (and the Pod formatter) know that this is where Perl code is
        resuming. (The blank line before the "=cut" is not technically necessary, but many older Pod
        processors require it.)

    "=pod"
        The "=pod" command by itself doesn't do much of anything, but it signals to Perl (and Pod
        formatters) that a Pod block starts here. A Pod block starts with *any* command paragraph,
        so a "=pod" command is usually used just when you want to start a Pod block with an ordinary
        paragraph or a verbatim paragraph. For example:

          =item stuff()

          This function does stuff.

          =cut

          sub stuff {
            ...
          }

          =pod

          Remember to check its return value, as in:

            stuff() || die "Couldn't do stuff!";

          =cut

    "=begin *formatname*"
    "=end *formatname*"
    "=for *formatname* *text...*"
        For, begin, and end will let you have regions of text/code/data that are not generally
        interpreted as normal Pod text, but are passed directly to particular formatters, or are
        otherwise special. A formatter that can use that format will use the region, otherwise it
        will be completely ignored.

        A command "=begin *formatname*", some paragraphs, and a command "=end *formatname*", mean
        that the text/data in between is meant for formatters that understand the special format
        called *formatname*. For example,

          =begin html

          <hr> <img src="thang.png">
          <p> This is a raw HTML paragraph </p>

          =end html

        The command "=for *formatname* *text...*" specifies that the remainder of just this
        paragraph (starting right after *formatname*) is in that special format.

          =for html <hr> <img src="thang.png">
          <p> This is a raw HTML paragraph </p>

        This means the same thing as the above "=begin html" ... "=end html" region.

        That is, with "=for", you can have only one paragraph's worth of text (i.e., the text in
        "=foo targetname text..."), but with "=begin targetname" ... "=end targetname", you can have
        any amount of stuff in between. (Note that there still must be a blank line after the
        "=begin" command and a blank line before the "=end" command.)

        Here are some examples of how to use these:

          =begin html

          <br>Figure 1.<br><IMG SRC="figure1.png"><br>

          =end html

          =begin text

            ---------------
            |  foo        |
            |        bar  |
            ---------------

          ^^^^ Figure 1. ^^^^

          =end text

        Some format names that formatters currently are known to accept include "roff", "man",
        "latex", "tex", "text", and "html". (Some formatters will treat some of these as synonyms.)

        A format name of "comment" is common for just making notes (presumably to yourself) that
        won't appear in any formatted version of the Pod document:

          =for comment
          Make sure that all the available options are documented!

        Some *formatnames* will require a leading colon (as in "=for :formatname", or "=begin
        :formatname" ... "=end :formatname"), to signal that the text is not raw data, but instead
        *is* Pod text (i.e., possibly containing formatting codes) that's just not for normal
        formatting (e.g., may not be a normal-use paragraph, but might be for formatting as a
        footnote).

    "=encoding *encodingname*"
        This command is used for declaring the encoding of a document. Most users won't need this;
        but if your encoding isn't US-ASCII, then put a "=encoding *encodingname*" command very
        early in the document so that pod formatters will know how to decode the document. For
        *encodingname*, use a name recognized by the [Encode::Supported](https://www.chedong.com/phpMan.php/perldoc/Encode%3A%3ASupported/markdown) module. Some pod formatters
        may try to guess between a Latin-1 or CP-1252 versus UTF-8 encoding, but they may guess
        wrong. It's best to be explicit if you use anything besides strict ASCII. Examples:

          =encoding latin1

          =encoding utf8

          =encoding koi8-r

          =encoding ShiftJIS

          =encoding big5

        "=encoding" affects the whole document, and must occur only once.

    And don't forget, all commands but "=encoding" last up until the end of its *paragraph*, not its
    line. So in the examples below, you can see that every command needs the blank line after it, to
    end its paragraph. (And some older Pod translators may require the "=encoding" line to have a
    following blank line as well, even though it should be legal to omit.)

    Some examples of lists include:

      =over

      =item *

      First item

      =item *

      Second item

      =back

      =over

      =item Foo()

      Description of Foo function

      =item Bar()

      Description of Bar function

      =back

### Formatting Codes
    In ordinary paragraphs and in some command paragraphs, various formatting codes (a.k.a.
    "interior sequences") can be used:

    "I<text>" -- italic text
        Used for emphasis (""be I<careful!>"") and parameters (""redo I<LABEL>"")

    "B<text>" -- bold text
        Used for switches (""perl's B<-n> switch""), programs (""some systems provide a B<chfn> for
        that""), emphasis (""be B<careful!>""), and so on (""and that feature is known as
        B<autovivification>"").

    "C<code>" -- code text
        Renders code in a typewriter font, or gives some other indication that this represents
        program text (""C<gmtime($^T)>"") or some other form of computerese (""C<drwxr-xr-x>"").

    "L<name>" -- a hyperlink
        There are various syntaxes, listed below. In the syntaxes given, "text", "name", and
        "section" cannot contain the characters '/' and '|'; and any '<' or '>' should be matched.

        *   "L<name>"

            Link to a Perl manual page (e.g., "L<[Net::Ping](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3APing/markdown)>"). Note that "name" should not contain
            spaces. This syntax is also occasionally used for references to Unix man pages, as in
            "L<[crontab(5)](https://www.chedong.com/phpMan.php/man/crontab/5/markdown)>".

        *   "L<name/"sec">" or "L<name/sec>"

            Link to a section in other manual page. E.g., "L<perlsyn/"For Loops">"

        *   "L</"sec">" or "L</sec>"

            Link to a section in this manual page. E.g., "L</"Object Methods">"

        A section is started by the named heading or item. For example, "L<perlvar/$.>" or
        "L<perlvar/"$.">" both link to the section started by ""=item $."" in perlvar. And
        "L<perlsyn/For Loops>" or "L<perlsyn/"For Loops">" both link to the section started by
        ""=head2 For Loops"" in perlsyn.

        To control what text is used for display, you use ""L<text|...>"", as in:

        *   "L<text|name>"

            Link this text to that manual page. E.g., "L<Perl Error Messages|perldiag>"

        *   "L<text|name/"sec">" or "L<text|name/sec>"

            Link this text to that section in that manual page. E.g., "L<postfix
            "if"|perlsyn/"Statement Modifiers">"

        *   "L<text|/"sec">" or "L<text|/sec>" or "L<text|"sec">"

            Link this text to that section in this manual page. E.g., "L<the various
            attributes|/"Member Data">"

        Or you can link to a web page:

        *   "L<scheme:...>"

            "L<text|scheme:...>"

            Links to an absolute URL. For example, "L<<http://www.perl.org/>>" or "L<The Perl Home
            Page|<http://www.perl.org/>>".

    "E<escape>" -- a character escape
        Very similar to HTML/XML "&*foo*;" "entity references":

        *   "E<lt>" -- a literal < (less than)

        *   "E<gt>" -- a literal > (greater than)

        *   "E<verbar>" -- a literal | (*ver*tical *bar*)

        *   "E<sol>" -- a literal / (*sol*idus)

            The above four are optional except in other formatting codes, notably "L<...>", and when
            preceded by a capital letter.

        *   "E<htmlname>"

            Some non-numeric HTML entity name, such as "E<eacute>", meaning the same thing as
            "&eacute;" in HTML -- i.e., a lowercase e with an acute (/-shaped) accent.

        *   "E<number>"

            The ASCII/Latin-1/Unicode character with that number. A leading "0x" means that *number*
            is hex, as in "E<0x201E>". A leading "0" means that *number* is octal, as in "E<075>".
            Otherwise *number* is interpreted as being in decimal, as in "E<181>".

            Note that older Pod formatters might not recognize octal or hex numeric escapes, and
            that many formatters cannot reliably render characters above 255. (Some formatters may
            even have to use compromised renderings of Latin-1/CP-1252 characters, like rendering
            "E<eacute>" as just a plain "e".)

    "F<filename>" -- used for filenames
        Typically displayed in italics. Example: ""F<.cshrc>""

    "S<text>" -- text contains non-breaking spaces
        This means that the words in *text* should not be broken across lines. Example:
        "S<$x ? $y : $z>".

    "X<topic name>" -- an index entry
        This is ignored by most formatters, but some may use it for building indexes. It always
        renders as empty-string. Example: "X<absolutizing relative URLs>"

    "Z<>" -- a null (zero-effect) formatting code
        This is rarely used. It's one way to get around using an E<...> code sometimes. For example,
        instead of ""NE<lt>3"" (for "N<3") you could write ""NZ<><3"" (the "Z<>" breaks up the "N"
        and the "<" so they can't be considered the part of a (fictitious) "N<...>" code).

        Another use is to indicate that *stuff* in "=item Z<>*stuff...*" is not to be considered to
        be a bullet or number. For example, without the "Z<>", the line

         =item Z<>500 Server error

        could possibly be parsed as an item in a numbered list when it isn't meant to be.

        Still another use is to maintain visual space between "=item" lines. If you specify

         =item foo

         =item bar

        it will typically get rendered as

         foo
         bar

        That may be what you want, but if what you really want is

         foo

         bar

        you can use "Z<>" to accomplish that

         =item foo

         Z<>

         =item bar

    Most of the time, you will need only a single set of angle brackets to delimit the beginning and
    end of formatting codes. However, sometimes you will want to put a real right angle bracket (a
    greater-than sign, '>') inside of a formatting code. This is particularly common when using a
    formatting code to provide a different font-type for a snippet of code. As with all things in
    Perl, there is more than one way to do it. One way is to simply escape the closing bracket using
    an "E" code:

        C<$a E<lt>=E<gt> $b>

    This will produce: ""$a <=> $b""

    A more readable, and perhaps more "plain" way is to use an alternate set of delimiters that
    doesn't require a single ">" to be escaped. Doubled angle brackets ("<<" and ">>") may be used
    *if and only if there is whitespace right after the opening delimiter and whitespace right
    before the closing delimiter!* For example, the following will do the trick:

        C<< $a <=> $b >>

    In fact, you can use as many repeated angle-brackets as you like so long as you have the same
    number of them in the opening and closing delimiters, and make sure that whitespace immediately
    follows the last '<' of the opening delimiter, and immediately precedes the first '>' of the
    closing delimiter. (The whitespace is ignored.) So the following will also work:

        C<<< $a <=> $b >>>
        C<<<<  $a <=> $b     >>>>

    And they all mean exactly the same as this:

        C<$a E<lt>=E<gt> $b>

    The multiple-bracket form does not affect the interpretation of the contents of the formatting
    code, only how it must end. That means that the examples above are also exactly the same as
    this:

        C<< $a E<lt>=E<gt> $b >>

    As a further example, this means that if you wanted to put these bits of code in "C" (code)
    style:

        open(X, ">>thing.dat") || die $!
        $foo->bar();

    you could do it like so:

        C<<< open(X, ">>thing.dat") || die $! >>>
        C<< $foo->bar(); >>

    which is presumably easier to read than the old way:

        C<open(X, "E<gt>E<gt>thing.dat") || die $!>
        C<$foo-E<gt>bar();>

    This is currently supported by pod2text ([Pod::Text](https://www.chedong.com/phpMan.php/perldoc/Pod%3A%3AText/markdown)), pod2man ([Pod::Man](https://www.chedong.com/phpMan.php/perldoc/Pod%3A%3AMan/markdown)), and any other pod2xxx
    or [Pod::Xxxx](https://www.chedong.com/phpMan.php/perldoc/Pod%3A%3AXxxx/markdown) translators that use [Pod::Parser](https://www.chedong.com/phpMan.php/perldoc/Pod%3A%3AParser/markdown) 1.093 or later, or [Pod::Tree](https://www.chedong.com/phpMan.php/perldoc/Pod%3A%3ATree/markdown) 1.02 or later.

### The Intent
    The intent is simplicity of use, not power of expression. Paragraphs look like paragraphs (block
    format), so that they stand out visually, and so that I could run them through "fmt" easily to
    reformat them (that's F7 in my version of vi, or Esc Q in my version of emacs). I wanted the
    translator to always leave the "'" and "`" and """ quotes alone, in verbatim mode, so I could
    slurp in a working program, shift it over four spaces, and have it print out, er, verbatim. And
    presumably in a monospace font.

    The Pod format is not necessarily sufficient for writing a book. Pod is just meant to be an
    idiot-proof common source for nroff, HTML, TeX, and other markup languages, as used for online
    documentation. Translators exist for pod2text, pod2html, pod2man (that's for [nroff(1)](https://www.chedong.com/phpMan.php/man/nroff/1/markdown) and
### troff

### Embedding Pods in Perl Modules
    You can embed Pod documentation in your Perl modules and scripts. Start your documentation with
    an empty line, a "=head1" command at the beginning, and end it with a "=cut" command and an
    empty line. The perl executable will ignore the Pod text. You can place a Pod statement where
    perl expects the beginning of a new statement, but not within a statement, as that would result
    in an error. See any of the supplied library modules for examples.

    If you're going to put your Pod at the end of the file, and you're using an "__END__" or
    "__DATA__" cut mark, make sure to put an empty line there before the first Pod command.

      __END__

      =head1 NAME

      [Time::Local](https://www.chedong.com/phpMan.php/perldoc/Time%3A%3ALocal/markdown) - efficiently compute time from local and GMT time

    Without that empty line before the "=head1", many translators wouldn't have recognized the
    "=head1" as starting a Pod block.

### Hints for Writing Pod
    *   The podchecker command is provided for checking Pod syntax for errors and warnings. For
        example, it checks for completely blank lines in Pod blocks and for unknown commands and
        formatting codes. You should still also pass your document through one or more translators
        and proofread the result, or print out the result and proofread that. Some of the problems
        found may be bugs in the translators, which you may or may not wish to work around.

    *   If you're more familiar with writing in HTML than with writing in Pod, you can try your hand
        at writing documentation in simple HTML, and converting it to Pod with the experimental
        [Pod::HTML2Pod](https://www.chedong.com/phpMan.php/perldoc/Pod%3A%3AHTML2Pod/markdown) module, (available in CPAN), and looking at the resulting code. The
        experimental [Pod::PXML](https://www.chedong.com/phpMan.php/perldoc/Pod%3A%3APXML/markdown) module in CPAN might also be useful.

    *   Many older Pod translators require the lines before every Pod command and after every Pod
        command (including "=cut"!) to be a blank line. Having something like this:

         # - - - - - - - - - - - -
         =item $firecracker->boom()

         This noisily detonates the firecracker object.
         =cut
         sub boom {
         ...

        ...will make such Pod translators completely fail to see the Pod block at all.

        Instead, have it like this:

         # - - - - - - - - - - - -

         =item $firecracker->boom()

         This noisily detonates the firecracker object.

         =cut

         sub boom {
         ...

    *   Some older Pod translators require paragraphs (including command paragraphs like "=head2
        Functions") to be separated by *completely* empty lines. If you have an apparently empty
        line with some spaces on it, this might not count as a separator for those translators, and
        that could cause odd formatting.

    *   Older translators might add wording around an L<> link, so that "L<[Foo::Bar](https://www.chedong.com/phpMan.php/perldoc/Foo%3A%3ABar/markdown)>" may become
        "the [Foo::Bar](https://www.chedong.com/phpMan.php/perldoc/Foo%3A%3ABar/markdown) manpage", for example. So you shouldn't write things like "the L<foo>
        documentation", if you want the translated document to read sensibly. Instead, write "the
        L<[Foo::Bar](https://www.chedong.com/phpMan.php/perldoc/Foo%3A%3ABar/markdown)|[Foo::Bar](https://www.chedong.com/phpMan.php/perldoc/Foo%3A%3ABar/markdown)> documentation" or "L<the [Foo::Bar](https://www.chedong.com/phpMan.php/perldoc/Foo%3A%3ABar/markdown) documentation|[Foo::Bar](https://www.chedong.com/phpMan.php/perldoc/Foo%3A%3ABar/markdown)>", to control
        how the link comes out.

    *   Going past the 70th column in a verbatim block might be ungracefully wrapped by some
        formatters.

## SEE ALSO
    perlpodspec, "PODs: Embedded Documentation" in perlsyn, perlnewmod, perldoc, pod2html, pod2man,
    podchecker.

## AUTHOR
    Larry Wall, Sean M. Burke