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            "text": "# perlpodspec (man)\n\n## NAME\n\nperlpodspec - Plain Old Documentation: format specification and notes\n\n## DESCRIPTION\n\nThis document is detailed notes on the Pod markup language.  Most people will only have to\nread perlpod to know how to write in Pod, but this document may answer some incidental\nquestions to do with parsing and rendering Pod.\n\n## Sections\n\n- **NAME**\n- **DESCRIPTION** (7 subsections)\n- **SEE ALSO**\n- **AUTHOR**\n\nUse structuredContent.sections for detailed options, examples, and full documentation.\n"
        }
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        "mode": "man",
        "summary": "perlpodspec - Plain Old Documentation: format specification and notes",
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        "section_outline": [
            {
                "name": "NAME",
                "lines": 2,
                "subsections": []
            },
            {
                "name": "DESCRIPTION",
                "lines": 17,
                "subsections": [
                    {
                        "name": "Pod Definitions",
                        "lines": 111
                    },
                    {
                        "name": "Pod Commands",
                        "lines": 138
                    },
                    {
                        "name": "Pod Formatting Codes",
                        "lines": 152
                    },
                    {
                        "name": "Notes on Implementing Pod Processors",
                        "lines": 365
                    },
                    {
                        "name": "About L<...> Codes",
                        "lines": 198
                    },
                    {
                        "name": "About =over...=back Regions",
                        "lines": 171
                    },
                    {
                        "name": "About Data Paragraphs and \"=begin/=end\" Regions",
                        "lines": 291
                    }
                ]
            },
            {
                "name": "SEE ALSO",
                "lines": 2,
                "subsections": []
            },
            {
                "name": "AUTHOR",
                "lines": 5,
                "subsections": []
            }
        ],
        "sections": {
            "NAME": {
                "content": "perlpodspec - Plain Old Documentation: format specification and notes\n",
                "subsections": []
            },
            "DESCRIPTION": {
                "content": "This document is detailed notes on the Pod markup language.  Most people will only have to\nread perlpod to know how to write in Pod, but this document may answer some incidental\nquestions to do with parsing and rendering Pod.\n\nIn this document, \"must\" / \"must not\", \"should\" / \"should not\", and \"may\" have their\nconventional (cf. RFC 2119) meanings: \"X must do Y\" means that if X doesn't do Y, it's\nagainst this specification, and should really be fixed.  \"X should do Y\" means that it's\nrecommended, but X may fail to do Y, if there's a good reason.  \"X may do Y\" is merely a note\nthat X can do Y at will (although it is up to the reader to detect any connotation of \"and I\nthink it would be nice if X did Y\" versus \"it wouldn't really bother me if X did Y\").\n\nNotably, when I say \"the parser should do Y\", the parser may fail to do Y, if the calling\napplication explicitly requests that the parser not do Y.  I often phrase this as \"the parser\nshould, by default, do Y.\"  This doesn't require the parser to provide an option for turning\noff whatever feature Y is (like expanding tabs in verbatim paragraphs), although it\nimplicates that such an option may be provided.\n",
                "subsections": [
                    {
                        "name": "Pod Definitions",
                        "content": "Pod is embedded in files, typically Perl source files, although you can write a file that's\nnothing but Pod.\n\nA line in a file consists of zero or more non-newline characters, terminated by either a\nnewline or the end of the file.\n\nA newline sequence is usually a platform-dependent concept, but Pod parsers should understand\nit to mean any of CR (ASCII 13), LF (ASCII 10), or a CRLF (ASCII 13 followed immediately by\nASCII 10), in addition to any other system-specific meaning.  The first CR/CRLF/LF sequence\nin the file may be used as the basis for identifying the newline sequence for parsing the\nrest of the file.\n\nA blank line is a line consisting entirely of zero or more spaces (ASCII 32) or tabs (ASCII\n9), and terminated by a newline or end-of-file.  A non-blank line is a line containing one or\nmore characters other than space or tab (and terminated by a newline or end-of-file).\n\n(Note: Many older Pod parsers did not accept a line consisting of spaces/tabs and then a\nnewline as a blank line. The only lines they considered blank were lines consisting of no\ncharacters at all, terminated by a newline.)\n\nWhitespace is used in this document as a blanket term for spaces, tabs, and newline\nsequences.  (By itself, this term usually refers to literal whitespace.  That is, sequences\nof whitespace characters in Pod source, as opposed to \"E<32>\", which is a formatting code\nthat denotes a whitespace character.)\n\nA Pod parser is a module meant for parsing Pod (regardless of whether this involves calling\ncallbacks or building a parse tree or directly formatting it).  A Pod formatter (or Pod\ntranslator) is a module or program that converts Pod to some other format (HTML, plaintext,\nTeX, PostScript, RTF).  A Pod processor might be a formatter or translator, or might be a\nprogram that does something else with the Pod (like counting words, scanning for index\npoints, etc.).\n\nPod content is contained in Pod blocks.  A Pod block starts with a line that matches\n\"m/\\A=[a-zA-Z]/\", and continues up to the next line that matches \"m/\\A=cut/\" or up to the end\nof the file if there is no \"m/\\A=cut/\" line.\n\nNote that a parser is not expected to distinguish between something that looks like pod, but\nis in a quoted string, such as a here document.\n\nWithin a Pod block, there are Pod paragraphs.  A Pod paragraph consists of non-blank lines of\ntext, separated by one or more blank lines.\n\nFor purposes of Pod processing, there are four types of paragraphs in a Pod block:\n\n•   A command paragraph (also called a \"directive\").  The first line of this paragraph must\nmatch \"m/\\A=[a-zA-Z]/\".  Command paragraphs are typically one line, as in:\n\n=head1 NOTES\n\n=item *\n\nBut they may span several (non-blank) lines:\n\n=for comment\nHm, I wonder what it would look like if\nyou tried to write a BNF for Pod from this.\n\n=head3 Dr. Strangelove, or: How I Learned to\nStop Worrying and Love the Bomb\n\nSome command paragraphs allow formatting codes in their content (i.e., after the part\nthat matches \"m/\\A=[a-zA-Z]\\S*\\s*/\"), as in:\n\n=head1 Did You Remember to C<use strict;>?\n\nIn other words, the Pod processing handler for \"head1\" will apply the same processing to\n\"Did You Remember to C<use strict;>?\" that it would to an ordinary paragraph (i.e.,\nformatting codes like \"C<...>\") are parsed and presumably formatted appropriately, and\nwhitespace in the form of literal spaces and/or tabs is not significant.\n\n•   A verbatim paragraph.  The first line of this paragraph must be a literal space or tab,\nand this paragraph must not be inside a \"=begin identifier\", ... \"=end identifier\"\nsequence unless \"identifier\" begins with a colon (\":\").  That is, if a paragraph starts\nwith a literal space or tab, but is inside a \"=begin identifier\", ... \"=end identifier\"\nregion, then it's a data paragraph, unless \"identifier\" begins with a colon.\n\nWhitespace is significant in verbatim paragraphs (although, in processing, tabs are\nprobably expanded).\n\n•   An ordinary paragraph.  A paragraph is an ordinary paragraph if its first line matches\nneither \"m/\\A=[a-zA-Z]/\" nor \"m/\\A[ \\t]/\", and if it's not inside a \"=begin identifier\",\n... \"=end identifier\" sequence unless \"identifier\" begins with a colon (\":\").\n\n•   A data paragraph.  This is a paragraph that is inside a \"=begin identifier\" ... \"=end\nidentifier\" sequence where \"identifier\" does not begin with a literal colon (\":\").  In\nsome sense, a data paragraph is not part of Pod at all (i.e., effectively it's \"out-of-\nband\"), since it's not subject to most kinds of Pod parsing; but it is specified here,\nsince Pod parsers need to be able to call an event for it, or store it in some form in a\nparse tree, or at least just parse around it.\n\nFor example: consider the following paragraphs:\n\n# <- that's the 0th column\n\n=head1 Foo\n\nStuff\n\n$foo->bar\n\n=cut\n\nHere, \"=head1 Foo\" and \"=cut\" are command paragraphs because the first line of each matches\n\"m/\\A=[a-zA-Z]/\".  \"[space][space]$foo->bar\" is a verbatim paragraph, because its first line\nstarts with a literal whitespace character (and there's no \"=begin\"...\"=end\" region around).\n\nThe \"=begin identifier\" ... \"=end identifier\" commands stop paragraphs that they surround\nfrom being parsed as ordinary or verbatim paragraphs, if identifier doesn't begin with a\ncolon.  This is discussed in detail in the section \"About Data Paragraphs and \"=begin/=end\"\nRegions\".\n"
                    },
                    {
                        "name": "Pod Commands",
                        "content": "This section is intended to supplement and clarify the discussion in \"Command Paragraph\" in\nperlpod.  These are the currently recognized Pod commands:\n\n\"=head1\", \"=head2\", \"=head3\", \"=head4\"\nThis command indicates that the text in the remainder of the paragraph is a heading.\nThat text may contain formatting codes.  Examples:\n\n=head1 Object Attributes\n\n=head3 What B<Not> to Do!\n\n\"=pod\"\nThis command indicates that this paragraph begins a Pod block.  (If we are already in the\nmiddle of a Pod block, this command has no effect at all.)  If there is any text in this\ncommand paragraph after \"=pod\", it must be ignored.  Examples:\n\n=pod\n\nThis is a plain Pod paragraph.\n\n=pod This text is ignored.\n\n\"=cut\"\nThis command indicates that this line is the end of this previously started Pod block.\nIf there is any text after \"=cut\" on the line, it must be ignored.  Examples:\n\n=cut\n\n=cut The documentation ends here.\n\n=cut\n# This is the first line of program text.\nsub foo { # This is the second.\n\nIt is an error to try to start a Pod block with a \"=cut\" command.  In that case, the Pod\nprocessor must halt parsing of the input file, and must by default emit a warning.\n\n\"=over\"\nThis command indicates that this is the start of a list/indent region.  If there is any\ntext following the \"=over\", it must consist of only a nonzero positive numeral.  The\nsemantics of this numeral is explained in the \"About =over...=back Regions\" section,\nfurther below.  Formatting codes are not expanded.  Examples:\n\n=over 3\n\n=over 3.5\n\n=over\n\n\"=item\"\nThis command indicates that an item in a list begins here.  Formatting codes are\nprocessed.  The semantics of the (optional) text in the remainder of this paragraph are\nexplained in the \"About =over...=back Regions\" section, further below.  Examples:\n\n=item\n\n=item *\n\n=item      *\n\n=item 14\n\n=item   3.\n\n=item C<< $thing->stuff(I<dodad>) >>\n\n=item For transporting us beyond seas to be tried for pretended\noffenses\n\n=item He is at this time transporting large armies of foreign\nmercenaries to complete the works of death, desolation and\ntyranny, already begun with circumstances of cruelty and perfidy\nscarcely paralleled in the most barbarous ages, and totally\nunworthy the head of a civilized nation.\n\n\"=back\"\nThis command indicates that this is the end of the region begun by the most recent\n\"=over\" command.  It permits no text after the \"=back\" command.\n\n\"=begin formatname\"\n\"=begin formatname parameter\"\nThis marks the following paragraphs (until the matching \"=end formatname\") as being for\nsome special kind of processing.  Unless \"formatname\" begins with a colon, the contained\nnon-command paragraphs are data paragraphs.  But if \"formatname\" does begin with a colon,\nthen non-command paragraphs are ordinary paragraphs or data paragraphs.  This is\ndiscussed in detail in the section \"About Data Paragraphs and \"=begin/=end\" Regions\".\n\nIt is advised that formatnames match the regexp \"m/\\A:?[-a-zA-Z0-9]+\\z/\".  Everything\nfollowing whitespace after the formatname is a parameter that may be used by the\nformatter when dealing with this region.  This parameter must not be repeated in the\n\"=end\" paragraph.  Implementors should anticipate future expansion in the semantics and\nsyntax of the first parameter to \"=begin\"/\"=end\"/\"=for\".\n\n\"=end formatname\"\nThis marks the end of the region opened by the matching \"=begin formatname\" region.  If\n\"formatname\" is not the formatname of the most recent open \"=begin formatname\" region,\nthen this is an error, and must generate an error message.  This is discussed in detail\nin the section \"About Data Paragraphs and \"=begin/=end\" Regions\".\n\n\"=for formatname text...\"\nThis is synonymous with:\n\n=begin formatname\n\ntext...\n\n=end formatname\n\nThat is, it creates a region consisting of a single paragraph; that paragraph is to be\ntreated as a normal paragraph if \"formatname\" begins with a \":\"; if \"formatname\" doesn't\nbegin with a colon, then \"text...\" will constitute a data paragraph.  There is no way to\nuse \"=for formatname text...\" to express \"text...\" as a verbatim paragraph.\n\n\"=encoding encodingname\"\nThis command, which should occur early in the document (at least before any non-US-ASCII\ndata!), declares that this document is encoded in the encoding encodingname, which must\nbe an encoding name that Encode recognizes.  (Encode's list of supported encodings, in\nEncode::Supported, is useful here.)  If the Pod parser cannot decode the declared\nencoding, it should emit a warning and may abort parsing the document altogether.\n\nA document having more than one \"=encoding\" line should be considered an error.  Pod\nprocessors may silently tolerate this if the not-first \"=encoding\" lines are just\nduplicates of the first one (e.g., if there's a \"=encoding utf8\" line, and later on\nanother \"=encoding utf8\" line).  But Pod processors should complain if there are\ncontradictory \"=encoding\" lines in the same document (e.g., if there is a \"=encoding\nutf8\" early in the document and \"=encoding big5\" later).  Pod processors that recognize\nBOMs may also complain if they see an \"=encoding\" line that contradicts the BOM (e.g., if\na document with a UTF-16LE BOM has an \"=encoding shiftjis\" line).\n\nIf a Pod processor sees any command other than the ones listed above (like \"=head\", or\n\"=haed1\", or \"=stuff\", or \"=cuttlefish\", or \"=w123\"), that processor must by default treat\nthis as an error.  It must not process the paragraph beginning with that command, must by\ndefault warn of this as an error, and may abort the parse.  A Pod parser may allow a way for\nparticular applications to add to the above list of known commands, and to stipulate, for\neach additional command, whether formatting codes should be processed.\n\nFuture versions of this specification may add additional commands.\n"
                    },
                    {
                        "name": "Pod Formatting Codes",
                        "content": "(Note that in previous drafts of this document and of perlpod, formatting codes were referred\nto as \"interior sequences\", and this term may still be found in the documentation for Pod\nparsers, and in error messages from Pod processors.)\n\nThere are two syntaxes for formatting codes:\n\n•   A formatting code starts with a capital letter (just US-ASCII [A-Z]) followed by a \"<\",\nany number of characters, and ending with the first matching \">\".  Examples:\n\nThat's what I<you> think!\n\nWhat's C<CORE::dump()> for?\n\nX<C<chmod> and C<unlink()> Under Different Operating Systems>\n\n•   A formatting code starts with a capital letter (just US-ASCII [A-Z]) followed by two or\nmore \"<\"'s, one or more whitespace characters, any number of characters, one or more\nwhitespace characters, and ending with the first matching sequence of two or more \">\"'s,\nwhere the number of \">\"'s equals the number of \"<\"'s in the opening of this formatting\ncode.  Examples:\n\nThat's what I<< you >> think!\n\nC<<< open(X, \">>thing.dat\") || die $! >>>\n\nB<< $foo->bar(); >>\n\nWith this syntax, the whitespace character(s) after the \"C<<<\" and before the \">>>\" (or\nwhatever letter) are not renderable. They do not signify whitespace, are merely part of\nthe formatting codes themselves.  That is, these are all synonymous:\n\nC<thing>\nC<< thing >>\nC<<           thing     >>\nC<<<   thing >>>\nC<<<<\nthing\n>>>>\n\nand so on.\n\nFinally, the multiple-angle-bracket form does not alter the interpretation of nested\nformatting codes, meaning that the following four example lines are identical in meaning:\n\nB<example: C<$a E<lt>=E<gt> $b>>\n\nB<example: C<< $a <=> $b >>>\n\nB<example: C<< $a E<lt>=E<gt> $b >>>\n\nB<<< example: C<< $a E<lt>=E<gt> $b >> >>>\n\nIn parsing Pod, a notably tricky part is the correct parsing of (potentially nested!)\nformatting codes.  Implementors should consult the code in the \"parsetext\" routine in\nPod::Parser as an example of a correct implementation.\n\n\"I<text>\" -- italic text\nSee the brief discussion in \"Formatting Codes\" in perlpod.\n\n\"B<text>\" -- bold text\nSee the brief discussion in \"Formatting Codes\" in perlpod.\n\n\"C<code>\" -- code text\nSee the brief discussion in \"Formatting Codes\" in perlpod.\n\n\"F<filename>\" -- style for filenames\nSee the brief discussion in \"Formatting Codes\" in perlpod.\n\n\"X<topic name>\" -- an index entry\nSee the brief discussion in \"Formatting Codes\" in perlpod.\n\nThis code is unusual in that most formatters completely discard this code and its\ncontent.  Other formatters will render it with invisible codes that can be used in\nbuilding an index of the current document.\n\n\"Z<>\" -- a null (zero-effect) formatting code\nDiscussed briefly in \"Formatting Codes\" in perlpod.\n\nThis code is unusual in that it should have no content.  That is, a processor may\ncomplain if it sees \"Z<potatoes>\".  Whether or not it complains, the potatoes text should\nignored.\n\n\"L<name>\" -- a hyperlink\nThe complicated syntaxes of this code are discussed at length in \"Formatting Codes\" in\nperlpod, and implementation details are discussed below, in \"About L<...> Codes\".\nParsing the contents of L<content> is tricky.  Notably, the content has to be checked for\nwhether it looks like a URL, or whether it has to be split on literal \"|\" and/or \"/\" (in\nthe right order!), and so on, before E<...> codes are resolved.\n\n\"E<escape>\" -- a character escape\nSee \"Formatting Codes\" in perlpod, and several points in \"Notes on Implementing Pod\nProcessors\".\n\n\"S<text>\" -- text contains non-breaking spaces\nThis formatting code is syntactically simple, but semantically complex.  What it means is\nthat each space in the printable content of this code signifies a non-breaking space.\n\nConsider:\n\nC<$x ? $y    :  $z>\n\nS<C<$x ? $y     :  $z>>\n\nBoth signify the monospace (c[ode] style) text consisting of \"$x\", one space, \"?\", one\nspace, \":\", one space, \"$z\".  The difference is that in the latter, with the S code,\nthose spaces are not \"normal\" spaces, but instead are non-breaking spaces.\n\nIf a Pod processor sees any formatting code other than the ones listed above (as in \"N<...>\",\nor \"Q<...>\", etc.), that processor must by default treat this as an error.  A Pod parser may\nallow a way for particular applications to add to the above list of known formatting codes; a\nPod parser might even allow a way to stipulate, for each additional command, whether it\nrequires some form of special processing, as L<...> does.\n\nFuture versions of this specification may add additional formatting codes.\n\nHistorical note:  A few older Pod processors would not see a \">\" as closing a \"C<\" code, if\nthe \">\" was immediately preceded by a \"-\".  This was so that this:\n\nC<$foo->bar>\n\nwould parse as equivalent to this:\n\nC<$foo-E<gt>bar>\n\ninstead of as equivalent to a \"C\" formatting code containing only \"$foo-\", and then a \"bar>\"\noutside the \"C\" formatting code.  This problem has since been solved by the addition of\nsyntaxes like this:\n\nC<< $foo->bar >>\n\nCompliant parsers must not treat \"->\" as special.\n\nFormatting codes absolutely cannot span paragraphs.  If a code is opened in one paragraph,\nand no closing code is found by the end of that paragraph, the Pod parser must close that\nformatting code, and should complain (as in \"Unterminated I code in the paragraph starting at\nline 123: 'Time objects are not...'\").  So these two paragraphs:\n\nI<I told you not to do this!\n\nDon't make me say it again!>\n\n...must not be parsed as two paragraphs in italics (with the I code starting in one paragraph\nand starting in another.)  Instead, the first paragraph should generate a warning, but that\naside, the above code must parse as if it were:\n\nI<I told you not to do this!>\n\nDon't make me say it again!E<gt>\n\n(In SGMLish jargon, all Pod commands are like block-level elements, whereas all Pod\nformatting codes are like inline-level elements.)\n"
                    },
                    {
                        "name": "Notes on Implementing Pod Processors",
                        "content": "The following is a long section of miscellaneous requirements and suggestions to do with Pod\nprocessing.\n\n•   Pod formatters should tolerate lines in verbatim blocks that are of any length, even if\nthat means having to break them (possibly several times, for very long lines) to avoid\ntext running off the side of the page.  Pod formatters may warn of such line-breaking.\nSuch warnings are particularly appropriate for lines are over 100 characters long, which\nare usually not intentional.\n\n•   Pod parsers must recognize all of the three well-known newline formats: CR, LF, and CRLF.\nSee perlport.\n\n•   Pod parsers should accept input lines that are of any length.\n\n•   Since Perl recognizes a Unicode Byte Order Mark at the start of files as signaling that\nthe file is Unicode encoded as in UTF-16 (whether big-endian or little-endian) or UTF-8,\nPod parsers should do the same.  Otherwise, the character encoding should be understood\nas being UTF-8 if the first highbit byte sequence in the file seems valid as a UTF-8\nsequence, or otherwise as CP-1252 (earlier versions of this specification used Latin-1\ninstead of CP-1252).\n\nFuture versions of this specification may specify how Pod can accept other encodings.\nPresumably treatment of other encodings in Pod parsing would be as in XML parsing:\nwhatever the encoding declared by a particular Pod file, content is to be stored in\nmemory as Unicode characters.\n\n•   The well known Unicode Byte Order Marks are as follows:  if the file begins with the two\nliteral byte values 0xFE 0xFF, this is the BOM for big-endian UTF-16.  If the file begins\nwith the two literal byte value 0xFF 0xFE, this is the BOM for little-endian UTF-16.  On\nan ASCII platform, if the file begins with the three literal byte values 0xEF 0xBB 0xBF,\nthis is the BOM for UTF-8.  A mechanism portable to EBCDIC platforms is to:\n\nmy $utf8bom = \"\\x{FEFF}\";\nutf8::encode($utf8bom);\n\n•   A naive, but often sufficient heuristic on ASCII platforms, for testing the first highbit\nbyte-sequence in a BOM-less file (whether in code or in Pod!), to see whether that\nsequence is valid as UTF-8 (RFC 2279) is to check whether that the first byte in the\nsequence is in the range 0xC2 - 0xFD and whether the next byte is in the range 0x80 -\n0xBF.  If so, the parser may conclude that this file is in UTF-8, and all highbit\nsequences in the file should be assumed to be UTF-8.  Otherwise the parser should treat\nthe file as being in CP-1252.  (A better check, and which works on EBCDIC platforms as\nwell, is to pass a copy of the sequence to utf8::decode() which performs a full validity\ncheck on the sequence and returns TRUE if it is valid UTF-8, FALSE otherwise.  This\nfunction is always pre-loaded, is fast because it is written in C, and will only get\ncalled at most once, so you don't need to avoid it out of performance concerns.)  In the\nunlikely circumstance that the first highbit sequence in a truly non-UTF-8 file happens\nto appear to be UTF-8, one can cater to our heuristic (as well as any more intelligent\nheuristic) by prefacing that line with a comment line containing a highbit sequence that\nis clearly not valid as UTF-8.  A line consisting of simply \"#\", an e-acute, and any non-\nhighbit byte, is sufficient to establish this file's encoding.\n\n•   Pod processors must treat a \"=for [label] [content...]\" paragraph as meaning the same\nthing as a \"=begin [label]\" paragraph, content, and an \"=end [label]\" paragraph.  (The\nparser may conflate these two constructs, or may leave them distinct, in the expectation\nthat the formatter will nevertheless treat them the same.)\n\n•   When rendering Pod to a format that allows comments (i.e., to nearly any format other\nthan plaintext), a Pod formatter must insert comment text identifying its name and\nversion number, and the name and version numbers of any modules it might be using to\nprocess the Pod.  Minimal examples:\n\n%% POD::Pod2PS v3.14159, using POD::Parser v1.92\n\n<!-- Pod::HTML v3.14159, using POD::Parser v1.92 -->\n\n{\\doccomm generated by Pod::Tree::RTF 3.14159 using Pod::Tree 1.08}\n\n.\\\" Pod::Man version 3.14159, using POD::Parser version 1.92\n\nFormatters may also insert additional comments, including: the release date of the Pod\nformatter program, the contact address for the author(s) of the formatter, the current\ntime, the name of input file, the formatting options in effect, version of Perl used,\netc.\n\nFormatters may also choose to note errors/warnings as comments, besides or instead of\nemitting them otherwise (as in messages to STDERR, or \"die\"ing).\n\n•   Pod parsers may emit warnings or error messages (\"Unknown E code E<zslig>!\") to STDERR\n(whether through printing to STDERR, or \"warn\"ing/\"carp\"ing, or \"die\"ing/\"croak\"ing), but\nmust allow suppressing all such STDERR output, and instead allow an option for reporting\nerrors/warnings in some other way, whether by triggering a callback, or noting errors in\nsome attribute of the document object, or some similarly unobtrusive mechanism -- or even\nby appending a \"Pod Errors\" section to the end of the parsed form of the document.\n\n•   In cases of exceptionally aberrant documents, Pod parsers may abort the parse.  Even\nthen, using \"die\"ing/\"croak\"ing is to be avoided; where possible, the parser library may\nsimply close the input file and add text like \"* Formatting Aborted *\" to the end of\nthe (partial) in-memory document.\n\n•   In paragraphs where formatting codes (like E<...>, B<...>) are understood (i.e., not\nverbatim paragraphs, but including ordinary paragraphs, and command paragraphs that\nproduce renderable text, like \"=head1\"), literal whitespace should generally be\nconsidered \"insignificant\", in that one literal space has the same meaning as any\n(nonzero) number of literal spaces, literal newlines, and literal tabs (as long as this\nproduces no blank lines, since those would terminate the paragraph).  Pod parsers should\ncompact literal whitespace in each processed paragraph, but may provide an option for\noverriding this (since some processing tasks do not require it), or may follow additional\nspecial rules (for example, specially treating period-space-space or period-newline\nsequences).\n\n•   Pod parsers should not, by default, try to coerce apostrophe (') and quote (\") into smart\nquotes (little 9's, 66's, 99's, etc), nor try to turn backtick (`) into anything else but\na single backtick character (distinct from an open quote character!), nor \"--\" into\nanything but two minus signs.  They must never do any of those things to text in C<...>\nformatting codes, and never ever to text in verbatim paragraphs.\n\n•   When rendering Pod to a format that has two kinds of hyphens (-), one that's a non-\nbreaking hyphen, and another that's a breakable hyphen (as in \"object-oriented\", which\ncan be split across lines as \"object-\", newline, \"oriented\"), formatters are encouraged\nto generally translate \"-\" to non-breaking hyphen, but may apply heuristics to convert\nsome of these to breaking hyphens.\n\n•   Pod formatters should make reasonable efforts to keep words of Perl code from being\nbroken across lines.  For example, \"Foo::Bar\" in some formatting systems is seen as\neligible for being broken across lines as \"Foo::\" newline \"Bar\" or even \"Foo::-\" newline\n\"Bar\".  This should be avoided where possible, either by disabling all line-breaking in\nmid-word, or by wrapping particular words with internal punctuation in \"don't break this\nacross lines\" codes (which in some formats may not be a single code, but might be a\nmatter of inserting non-breaking zero-width spaces between every pair of characters in a\nword.)\n\n•   Pod parsers should, by default, expand tabs in verbatim paragraphs as they are processed,\nbefore passing them to the formatter or other processor.  Parsers may also allow an\noption for overriding this.\n\n•   Pod parsers should, by default, remove newlines from the end of ordinary and verbatim\nparagraphs before passing them to the formatter.  For example, while the paragraph you're\nreading now could be considered, in Pod source, to end with (and contain) the newline(s)\nthat end it, it should be processed as ending with (and containing) the period character\nthat ends this sentence.\n\n•   Pod parsers, when reporting errors, should make some effort to report an approximate line\nnumber (\"Nested E<>'s in Paragraph #52, near line 633 of Thing/Foo.pm!\"), instead of\nmerely noting the paragraph number (\"Nested E<>'s in Paragraph #52 of Thing/Foo.pm!\").\nWhere this is problematic, the paragraph number should at least be accompanied by an\nexcerpt from the paragraph (\"Nested E<>'s in Paragraph #52 of Thing/Foo.pm, which begins\n'Read/write accessor for the C<interest rate> attribute...'\").\n\n•   Pod parsers, when processing a series of verbatim paragraphs one after another, should\nconsider them to be one large verbatim paragraph that happens to contain blank lines.\nI.e., these two lines, which have a blank line between them:\n\nuse Foo;\n\nprint Foo->VERSION\n\nshould be unified into one paragraph (\"\\tuse Foo;\\n\\n\\tprint Foo->VERSION\") before being\npassed to the formatter or other processor.  Parsers may also allow an option for\noverriding this.\n\nWhile this might be too cumbersome to implement in event-based Pod parsers, it is\nstraightforward for parsers that return parse trees.\n\n•   Pod formatters, where feasible, are advised to avoid splitting short verbatim paragraphs\n(under twelve lines, say) across pages.\n\n•   Pod parsers must treat a line with only spaces and/or tabs on it as a \"blank line\" such\nas separates paragraphs.  (Some older parsers recognized only two adjacent newlines as a\n\"blank line\" but would not recognize a newline, a space, and a newline, as a blank line.\nThis is noncompliant behavior.)\n\n•   Authors of Pod formatters/processors should make every effort to avoid writing their own\nPod parser.  There are already several in CPAN, with a wide range of interface styles --\nand one of them, Pod::Simple, comes with modern versions of Perl.\n\n•   Characters in Pod documents may be conveyed either as literals, or by number in E<n>\ncodes, or by an equivalent mnemonic, as in E<eacute> which is exactly equivalent to\nE<233>.  The numbers are the Latin1/Unicode values, even on EBCDIC platforms.\n\nWhen referring to characters by using a E<n> numeric code, numbers in the range 32-126\nrefer to those well known US-ASCII characters (also defined there by Unicode, with the\nsame meaning), which all Pod formatters must render faithfully.  Characters whose E<>\nnumbers are in the ranges 0-31 and 127-159 should not be used (neither as literals, nor\nas E<number> codes), except for the literal byte-sequences for newline (ASCII 13, ASCII\n13 10, or ASCII 10), and tab (ASCII 9).\n\nNumbers in the range 160-255 refer to Latin-1 characters (also defined there by Unicode,\nwith the same meaning).  Numbers above 255 should be understood to refer to Unicode\ncharacters.\n\n•   Be warned that some formatters cannot reliably render characters outside 32-126; and many\nare able to handle 32-126 and 160-255, but nothing above 255.\n\n•   Besides the well-known \"E<lt>\" and \"E<gt>\" codes for less-than and greater-than, Pod\nparsers must understand \"E<sol>\" for \"/\" (solidus, slash), and \"E<verbar>\" for \"|\"\n(vertical bar, pipe).  Pod parsers should also understand \"E<lchevron>\" and \"E<rchevron>\"\nas legacy codes for characters 171 and 187, i.e., \"left-pointing double angle quotation\nmark\" = \"left pointing guillemet\" and \"right-pointing double angle quotation mark\" =\n\"right pointing guillemet\".  (These look like little \"<<\" and \">>\", and they are now\npreferably expressed with the HTML/XHTML codes \"E<laquo>\" and \"E<raquo>\".)\n\n•   Pod parsers should understand all \"E<html>\" codes as defined in the entity declarations\nin the most recent XHTML specification at \"www.W3.org\".  Pod parsers must understand at\nleast the entities that define characters in the range 160-255 (Latin-1).  Pod parsers,\nwhen faced with some unknown \"E<identifier>\" code, shouldn't simply replace it with\nnullstring (by default, at least), but may pass it through as a string consisting of the\nliteral characters E, less-than, identifier, greater-than.  Or Pod parsers may offer the\nalternative option of processing such unknown \"E<identifier>\" codes by firing an event\nespecially for such codes, or by adding a special node-type to the in-memory document\ntree.  Such \"E<identifier>\" may have special meaning to some processors, or some\nprocessors may choose to add them to a special error report.\n\n•   Pod parsers must also support the XHTML codes \"E<quot>\" for character 34 (doublequote,\n\"), \"E<amp>\" for character 38 (ampersand, &), and \"E<apos>\" for character 39 (apostrophe,\n').\n\n•   Note that in all cases of \"E<whatever>\", whatever (whether an htmlname, or a number in\nany base) must consist only of alphanumeric characters -- that is, whatever must match\n\"m/\\A\\w+\\z/\".  So \"E< 0 1 2 3 >\" is invalid, because it contains spaces, which aren't\nalphanumeric characters.  This presumably does not need special treatment by a Pod\nprocessor; \" 0 1 2 3 \" doesn't look like a number in any base, so it would presumably be\nlooked up in the table of HTML-like names.  Since there isn't (and cannot be) an HTML-\nlike entity called \" 0 1 2 3 \", this will be treated as an error.  However, Pod\nprocessors may treat \"E< 0 1 2 3 >\" or \"E<e-acute>\" as syntactically invalid, potentially\nearning a different error message than the error message (or warning, or event) generated\nby a merely unknown (but theoretically valid) htmlname, as in \"E<qacute>\" [sic].\nHowever, Pod parsers are not required to make this distinction.\n\n•   Note that E<number> must not be interpreted as simply \"codepoint number in the\ncurrent/native character set\".  It always means only \"the character represented by\ncodepoint number in Unicode.\"  (This is identical to the semantics of &#number; in XML.)\n\nThis will likely require many formatters to have tables mapping from treatable Unicode\ncodepoints (such as the \"\\xE9\" for the e-acute character) to the escape sequences or\ncodes necessary for conveying such sequences in the target output format.  A converter to\n*roff would, for example know that \"\\xE9\" (whether conveyed literally, or via a E<...>\nsequence) is to be conveyed as \"e\\\\*'\".  Similarly, a program rendering Pod in a Mac OS\napplication window, would presumably need to know that \"\\xE9\" maps to codepoint 142 in\nMacRoman encoding that (at time of writing) is native for Mac OS.  Such Unicode2whatever\nmappings are presumably already widely available for common output formats.  (Such\nmappings may be incomplete!  Implementers are not expected to bend over backwards in an\nattempt to render Cherokee syllabics, Etruscan runes, Byzantine musical symbols, or any\nof the other weird things that Unicode can encode.)  And if a Pod document uses a\ncharacter not found in such a mapping, the formatter should consider it an unrenderable\ncharacter.\n\n•   If, surprisingly, the implementor of a Pod formatter can't find a satisfactory pre-\nexisting table mapping from Unicode characters to escapes in the target format (e.g., a\ndecent table of Unicode characters to *roff escapes), it will be necessary to build such\na table.  If you are in this circumstance, you should begin with the characters in the\nrange 0x00A0 - 0x00FF, which is mostly the heavily used accented characters.  Then\nproceed (as patience permits and fastidiousness compels) through the characters that the\n(X)HTML standards groups judged important enough to merit mnemonics for.  These are\ndeclared in the (X)HTML specifications at the www.W3.org site.  At time of writing\n(September 2001), the most recent entity declaration files are:\n\nhttp://www.w3.org/TR/xhtml1/DTD/xhtml-lat1.ent\nhttp://www.w3.org/TR/xhtml1/DTD/xhtml-special.ent\nhttp://www.w3.org/TR/xhtml1/DTD/xhtml-symbol.ent\n\nThen you can progress through any remaining notable Unicode characters in the range\n0x2000-0x204D (consult the character tables at www.unicode.org), and whatever else\nstrikes your fancy.  For example, in xhtml-symbol.ent, there is the entry:\n\n<!ENTITY infin    \"&#8734;\"> <!-- infinity, U+221E ISOtech -->\n\nWhile the mapping \"infin\" to the character \"\\x{221E}\" will (hopefully) have been already\nhandled by the Pod parser, the presence of the character in this file means that it's\nreasonably important enough to include in a formatter's table that maps from notable\nUnicode characters to the codes necessary for rendering them.  So for a Unicode-to-*roff\nmapping, for example, this would merit the entry:\n\n\"\\x{221E}\" => '\\(in',\n\nIt is eagerly hoped that in the future, increasing numbers of formats (and formatters)\nwill support Unicode characters directly (as (X)HTML does with \"&infin;\", \"&#8734;\", or\n\"&#x221E;\"), reducing the need for idiosyncratic mappings of Unicode-to-myescapes.\n\n•   It is up to individual Pod formatter to display good judgement when confronted with an\nunrenderable character (which is distinct from an unknown E<thing> sequence that the\nparser couldn't resolve to anything, renderable or not).  It is good practice to map\nLatin letters with diacritics (like \"E<eacute>\"/\"E<233>\") to the corresponding unaccented\nUS-ASCII letters (like a simple character 101, \"e\"), but clearly this is often not\nfeasible, and an unrenderable character may be represented as \"?\", or the like.  In\nattempting a sane fallback (as from E<233> to \"e\"), Pod formatters may use the\n%Latin1Codetofallback table in Pod::Escapes, or Text::Unidecode, if available.\n\nFor example, this Pod text:\n\nmagic is enabled if you set C<$Currency> to 'E<euro>'.\n\nmay be rendered as: \"magic is enabled if you set $Currency to '?'\" or as \"magic is\nenabled if you set $Currency to '[euro]'\", or as \"magic is enabled if you set $Currency\nto '[x20AC]', etc.\n\nA Pod formatter may also note, in a comment or warning, a list of what unrenderable\ncharacters were encountered.\n\n•   E<...> may freely appear in any formatting code (other than in another E<...> or in an\nZ<>).  That is, \"X<The E<euro>1,000,000 Solution>\" is valid, as is \"L<The\nE<euro>1,000,000 Solution|Million::Euros>\".\n\n•   Some Pod formatters output to formats that implement non-breaking spaces as an individual\ncharacter (which I'll call \"NBSP\"), and others output to formats that implement non-\nbreaking spaces just as spaces wrapped in a \"don't break this across lines\" code.  Note\nthat at the level of Pod, both sorts of codes can occur: Pod can contain a NBSP character\n(whether as a literal, or as a \"E<160>\" or \"E<nbsp>\" code); and Pod can contain \"S<foo\nI<bar> baz>\" codes, where \"mere spaces\" (character 32) in such codes are taken to\nrepresent non-breaking spaces.  Pod parsers should consider supporting the optional\nparsing of \"S<foo I<bar> baz>\" as if it were \"fooNBSPI<bar>NBSPbaz\", and, going the other\nway, the optional parsing of groups of words joined by NBSP's as if each group were in a\nS<...> code, so that formatters may use the representation that maps best to what the\noutput format demands.\n\n•   Some processors may find that the \"S<...>\" code is easiest to implement by replacing each\nspace in the parse tree under the content of the S, with an NBSP.  But note: the\nreplacement should apply not to spaces in all text, but only to spaces in printable text.\n(This distinction may or may not be evident in the particular tree/event model\nimplemented by the Pod parser.)  For example, consider this unusual case:\n\nS<L</Autoloaded Functions>>\n\nThis means that the space in the middle of the visible link text must not be broken\nacross lines.  In other words, it's the same as this:\n\nL<\"AutoloadedE<160>Functions\"/Autoloaded Functions>\n\nHowever, a misapplied space-to-NBSP replacement could (wrongly) produce something\nequivalent to this:\n\nL<\"AutoloadedE<160>Functions\"/AutoloadedE<160>Functions>\n\n...which is almost definitely not going to work as a hyperlink (assuming this formatter\noutputs a format supporting hypertext).\n\nFormatters may choose to just not support the S format code, especially in cases where\nthe output format simply has no NBSP character/code and no code for \"don't break this\nstuff across lines\".\n\n•   Besides the NBSP character discussed above, implementors are reminded of the existence of\nthe other \"special\" character in Latin-1, the \"soft hyphen\" character, also known as\n\"discretionary hyphen\", i.e. \"E<173>\" = \"E<0xAD>\" = \"E<shy>\").  This character expresses\nan optional hyphenation point.  That is, it normally renders as nothing, but may render\nas a \"-\" if a formatter breaks the word at that point.  Pod formatters should, as\nappropriate, do one of the following:  1) render this with a code with the same meaning\n(e.g., \"\\-\" in RTF), 2) pass it through in the expectation that the formatter understands\nthis character as such, or 3) delete it.\n\nFor example:\n\nsigE<shy>action\nmanuE<shy>script\nJarkE<shy>ko HieE<shy>taE<shy>nieE<shy>mi\n\nThese signal to a formatter that if it is to hyphenate \"sigaction\" or \"manuscript\", then\nit should be done as \"sig-[linebreak]action\" or \"manu-[linebreak]script\" (and if it\ndoesn't hyphenate it, then the \"E<shy>\" doesn't show up at all).  And if it is to\nhyphenate \"Jarkko\" and/or \"Hietaniemi\", it can do so only at the points where there is a\n\"E<shy>\" code.\n\nIn practice, it is anticipated that this character will not be used often, but formatters\nshould either support it, or delete it.\n\n•   If you think that you want to add a new command to Pod (like, say, a \"=biblio\" command),\nconsider whether you could get the same effect with a for or begin/end sequence: \"=for\nbiblio ...\" or \"=begin biblio\" ... \"=end biblio\".  Pod processors that don't understand\n\"=for biblio\", etc, will simply ignore it, whereas they may complain loudly if they see\n\"=biblio\".\n\n•   Throughout this document, \"Pod\" has been the preferred spelling for the name of the\ndocumentation format.  One may also use \"POD\" or \"pod\".  For the documentation that is\n(typically) in the Pod format, you may use \"pod\", or \"Pod\", or \"POD\".  Understanding\nthese distinctions is useful; but obsessing over how to spell them, usually is not.\n"
                    },
                    {
                        "name": "About L<...> Codes",
                        "content": "As you can tell from a glance at perlpod, the L<...> code is the most complex of the Pod\nformatting codes.  The points below will hopefully clarify what it means and how processors\nshould deal with it.\n\n•   In parsing an L<...> code, Pod parsers must distinguish at least four attributes:\n\nFirst:\nThe link-text.  If there is none, this must be \"undef\".  (E.g., in \"L<Perl\nFunctions|perlfunc>\", the link-text is \"Perl Functions\".  In \"L<Time::HiRes>\" and\neven \"L<|Time::HiRes>\", there is no link text.  Note that link text may contain\nformatting.)\n\nSecond:\nThe possibly inferred link-text; i.e., if there was no real link text, then this is\nthe text that we'll infer in its place.  (E.g., for \"L<Getopt::Std>\", the inferred\nlink text is \"Getopt::Std\".)\n\nThird:\nThe name or URL, or \"undef\" if none.  (E.g., in \"L<Perl Functions|perlfunc>\", the\nname (also sometimes called the page) is \"perlfunc\".  In \"L</CAVEATS>\", the name is\n\"undef\".)\n\nFourth:\nThe section (AKA \"item\" in older perlpods), or \"undef\" if none.  E.g., in\n\"L<Getopt::Std/DESCRIPTION>\", \"DESCRIPTION\" is the section.  (Note that this is not\nthe same as a manpage section like the \"5\" in \"man 5 crontab\".  \"Section Foo\" in the\nPod sense means the part of the text that's introduced by the heading or item whose\ntext is \"Foo\".)\n\nPod parsers may also note additional attributes including:\n\nFifth:\nA flag for whether item 3 (if present) is a URL (like \"http://lists.perl.org\" is), in\nwhich case there should be no section attribute; a Pod name (like \"perldoc\" and\n\"Getopt::Std\" are); or possibly a man page name (like \"crontab(5)\" is).\n\nSixth:\nThe raw original L<...> content, before text is split on \"|\", \"/\", etc, and before\nE<...> codes are expanded.\n\n(The above were numbered only for concise reference below.  It is not a requirement that\nthese be passed as an actual list or array.)\n\nFor example:\n\nL<Foo::Bar>\n=>  undef,                         # link text\n\"Foo::Bar\",                    # possibly inferred link text\n\"Foo::Bar\",                    # name\nundef,                         # section\n'pod',                         # what sort of link\n\"Foo::Bar\"                     # original content\n\nL<Perlport's section on NL's|perlport/Newlines>\n=>  \"Perlport's section on NL's\",  # link text\n\"Perlport's section on NL's\",  # possibly inferred link text\n\"perlport\",                    # name\n\"Newlines\",                    # section\n'pod',                         # what sort of link\n\"Perlport's section on NL's|perlport/Newlines\"\n# original content\n\nL<perlport/Newlines>\n=>  undef,                         # link text\n'\"Newlines\" in perlport',      # possibly inferred link text\n\"perlport\",                    # name\n\"Newlines\",                    # section\n'pod',                         # what sort of link\n\"perlport/Newlines\"            # original content\n\nL<crontab(5)/\"DESCRIPTION\">\n=>  undef,                         # link text\n'\"DESCRIPTION\" in crontab(5)', # possibly inferred link text\n\"crontab(5)\",                  # name\n\"DESCRIPTION\",                 # section\n'man',                         # what sort of link\n'crontab(5)/\"DESCRIPTION\"'     # original content\n\nL</Object Attributes>\n=>  undef,                         # link text\n'\"Object Attributes\"',         # possibly inferred link text\nundef,                         # name\n\"Object Attributes\",           # section\n'pod',                         # what sort of link\n\"/Object Attributes\"           # original content\n\nL<https://www.perl.org/>\n=>  undef,                         # link text\n\"https://www.perl.org/\",       # possibly inferred link text\n\"https://www.perl.org/\",       # name\nundef,                         # section\n'url',                         # what sort of link\n\"https://www.perl.org/\"         # original content\n\nL<Perl.org|https://www.perl.org/>\n=>  \"Perl.org\",                    # link text\n\"https://www.perl.org/\",       # possibly inferred link text\n\"https://www.perl.org/\",       # name\nundef,                         # section\n'url',                         # what sort of link\n\"Perl.org|https://www.perl.org/\" # original content\n\nNote that you can distinguish URL-links from anything else by the fact that they match\n\"m/\\A\\w+:[^:\\s]\\S*\\z/\".  So \"L<http://www.perl.com>\" is a URL, but \"L<HTTP::Response>\"\nisn't.\n\n•   In case of L<...> codes with no \"text|\" part in them, older formatters have exhibited\ngreat variation in actually displaying the link or cross reference.  For example,\nL<crontab(5)> would render as \"the crontab(5) manpage\", or \"in the crontab(5) manpage\" or\njust \"crontab(5)\".\n\nPod processors must now treat \"text|\"-less links as follows:\n\nL<name>         =>  L<name|name>\nL</section>     =>  L<\"section\"|/section>\nL<name/section> =>  L<\"section\" in name|name/section>\n\n•   Note that section names might contain markup.  I.e., if a section starts with:\n\n=head2 About the C<-M> Operator\n\nor with:\n\n=item About the C<-M> Operator\n\nthen a link to it would look like this:\n\nL<somedoc/About the C<-M> Operator>\n\nFormatters may choose to ignore the markup for purposes of resolving the link and use\nonly the renderable characters in the section name, as in:\n\n<h1><a name=\"Aboutthe-MOperator\">About the <code>-M</code>\nOperator</h1>\n\n...\n\n<a href=\"somedoc#Aboutthe-MOperator\">About the <code>-M</code>\nOperator\" in somedoc</a>\n\n•   Previous versions of perlpod distinguished \"L<name/\"section\">\" links from \"L<name/item>\"\nlinks (and their targets).  These have been merged syntactically and semantically in the\ncurrent specification, and section can refer either to a \"=headn Heading Content\" command\nor to a \"=item Item Content\" command.  This specification does not specify what behavior\nshould be in the case of a given document having several things all seeming to produce\nthe same section identifier (e.g., in HTML, several things all producing the same\nanchorname in <a name=\"anchorname\">...</a> elements).  Where Pod processors can control\nthis behavior, they should use the first such anchor.  That is, \"L<Foo/Bar>\" refers to\nthe first \"Bar\" section in Foo.\n\nBut for some processors/formats this cannot be easily controlled; as with the HTML\nexample, the behavior of multiple ambiguous <a name=\"anchorname\">...</a> is most easily\njust left up to browsers to decide.\n\n•   In a \"L<text|...>\" code, text may contain formatting codes for formatting or for E<...>\nescapes, as in:\n\nL<B<ummE<234>stuff>|...>\n\nFor \"L<...>\" codes without a \"name|\" part, only \"E<...>\" and \"Z<>\" codes may occur.  That\nis, authors should not use \"\"L<B<Foo::Bar>>\"\".\n\nNote, however, that formatting codes and Z<>'s can occur in any and all parts of an\nL<...> (i.e., in name, section, text, and url).\n\nAuthors must not nest L<...> codes.  For example, \"L<The L<Foo::Bar> man page>\" should be\ntreated as an error.\n\n•   Note that Pod authors may use formatting codes inside the \"text\" part of \"L<text|name>\"\n(and so on for L<text|/\"sec\">).\n\nIn other words, this is valid:\n\nGo read L<the docs on C<$.>|perlvar/\"$.\">\n\nSome output formats that do allow rendering \"L<...>\" codes as hypertext, might not allow\nthe link-text to be formatted; in that case, formatters will have to just ignore that\nformatting.\n\n•   At time of writing, \"L<name>\" values are of two types: either the name of a Pod page like\n\"L<Foo::Bar>\" (which might be a real Perl module or program in an @INC / PATH directory,\nor a .pod file in those places); or the name of a Unix man page, like \"L<crontab(5)>\".\nIn theory, \"L<chmod>\" is ambiguous between a Pod page called \"chmod\", or the Unix man\npage \"chmod\" (in whatever man-section).  However, the presence of a string in parens, as\nin \"crontab(5)\", is sufficient to signal that what is being discussed is not a Pod page,\nand so is presumably a Unix man page.  The distinction is of no importance to many Pod\nprocessors, but some processors that render to hypertext formats may need to distinguish\nthem in order to know how to render a given \"L<foo>\" code.\n\n•   Previous versions of perlpod allowed for a \"L<section>\" syntax (as in \"L<Object\nAttributes>\"), which was not easily distinguishable from \"L<name>\" syntax and for\n\"L<\"section\">\" which was only slightly less ambiguous.  This syntax is no longer in the\nspecification, and has been replaced by the \"L</section>\" syntax (where the slash was\nformerly optional).  Pod parsers should tolerate the \"L<\"section\">\" syntax, for a while\nat least.  The suggested heuristic for distinguishing \"L<section>\" from \"L<name>\" is that\nif it contains any whitespace, it's a section.  Pod processors should warn about this\nbeing deprecated syntax.\n"
                    },
                    {
                        "name": "About =over...=back Regions",
                        "content": "\"=over\"...\"=back\" regions are used for various kinds of list-like structures.  (I use the\nterm \"region\" here simply as a collective term for everything from the \"=over\" to the\nmatching \"=back\".)\n\n•   The non-zero numeric indentlevel in \"=over indentlevel\" ...  \"=back\" is used for giving\nthe formatter a clue as to how many \"spaces\" (ems, or roughly equivalent units) it should\ntab over, although many formatters will have to convert this to an absolute measurement\nthat may not exactly match with the size of spaces (or M's) in the document's base font.\nOther formatters may have to completely ignore the number.  The lack of any explicit\nindentlevel parameter is equivalent to an indentlevel value of 4.  Pod processors may\ncomplain if indentlevel is present but is not a positive number matching\n\"m/\\A(\\d*\\.)?\\d+\\z/\".\n\n•   Authors of Pod formatters are reminded that \"=over\" ... \"=back\" may map to several\ndifferent constructs in your output format.  For example, in converting Pod to (X)HTML,\nit can map to any of <ul>...</ul>, <ol>...</ol>, <dl>...</dl>, or\n<blockquote>...</blockquote>.  Similarly, \"=item\" can map to <li> or <dt>.\n\n•   Each \"=over\" ... \"=back\" region should be one of the following:\n\n•   An \"=over\" ... \"=back\" region containing only \"=item *\" commands, each followed by\nsome number of ordinary/verbatim paragraphs, other nested \"=over\" ... \"=back\"\nregions, \"=for...\" paragraphs, and \"=begin\"...\"=end\" regions.\n\n(Pod processors must tolerate a bare \"=item\" as if it were \"=item *\".)  Whether \"*\"\nis rendered as a literal asterisk, an \"o\", or as some kind of real bullet character,\nis left up to the Pod formatter, and may depend on the level of nesting.\n\n•   An \"=over\" ... \"=back\" region containing only \"m/\\A=item\\s+\\d+\\.?\\s*\\z/\" paragraphs,\neach one (or each group of them) followed by some number of ordinary/verbatim\nparagraphs, other nested \"=over\" ... \"=back\" regions, \"=for...\" paragraphs, and/or\n\"=begin\"...\"=end\" codes.  Note that the numbers must start at 1 in each section, and\nmust proceed in order and without skipping numbers.\n\n(Pod processors must tolerate lines like \"=item 1\" as if they were \"=item 1.\", with\nthe period.)\n\n•   An \"=over\" ... \"=back\" region containing only \"=item [text]\" commands, each one (or\neach group of them) followed by some number of ordinary/verbatim paragraphs, other\nnested \"=over\" ... \"=back\" regions, or \"=for...\" paragraphs, and \"=begin\"...\"=end\"\nregions.\n\nThe \"=item [text]\" paragraph should not match \"m/\\A=item\\s+\\d+\\.?\\s*\\z/\" or\n\"m/\\A=item\\s+\\*\\s*\\z/\", nor should it match just \"m/\\A=item\\s*\\z/\".\n\n•   An \"=over\" ... \"=back\" region containing no \"=item\" paragraphs at all, and containing\nonly some number of ordinary/verbatim paragraphs, and possibly also some nested\n\"=over\" ... \"=back\" regions, \"=for...\" paragraphs, and \"=begin\"...\"=end\" regions.\nSuch an itemless \"=over\" ... \"=back\" region in Pod is equivalent in meaning to a\n\"<blockquote>...</blockquote>\" element in HTML.\n\nNote that with all the above cases, you can determine which type of \"=over\" ... \"=back\"\nyou have, by examining the first (non-\"=cut\", non-\"=pod\") Pod paragraph after the \"=over\"\ncommand.\n\n•   Pod formatters must tolerate arbitrarily large amounts of text in the \"=item text...\"\nparagraph.  In practice, most such paragraphs are short, as in:\n\n=item For cutting off our trade with all parts of the world\n\nBut they may be arbitrarily long:\n\n=item For transporting us beyond seas to be tried for pretended\noffenses\n\n=item He is at this time transporting large armies of foreign\nmercenaries to complete the works of death, desolation and\ntyranny, already begun with circumstances of cruelty and perfidy\nscarcely paralleled in the most barbarous ages, and totally\nunworthy the head of a civilized nation.\n\n•   Pod processors should tolerate \"=item *\" / \"=item number\" commands with no accompanying\nparagraph.  The middle item is an example:\n\n=over\n\n=item 1\n\nPick up dry cleaning.\n\n=item 2\n\n=item 3\n\nStop by the store.  Get Abba Zabas, Stoli, and cheap lawn chairs.\n\n=back\n\n•   No \"=over\" ... \"=back\" region can contain headings.  Processors may treat such a heading\nas an error.\n\n•   Note that an \"=over\" ... \"=back\" region should have some content.  That is, authors\nshould not have an empty region like this:\n\n=over\n\n=back\n\nPod processors seeing such a contentless \"=over\" ... \"=back\" region, may ignore it, or\nmay report it as an error.\n\n•   Processors must tolerate an \"=over\" list that goes off the end of the document (i.e.,\nwhich has no matching \"=back\"), but they may warn about such a list.\n\n•   Authors of Pod formatters should note that this construct:\n\n=item Neque\n\n=item Porro\n\n=item Quisquam Est\n\nQui dolorem ipsum quia dolor sit amet, consectetur, adipisci\nvelit, sed quia non numquam eius modi tempora incidunt ut\nlabore et dolore magnam aliquam quaerat voluptatem.\n\n=item Ut Enim\n\nis semantically ambiguous, in a way that makes formatting decisions a bit difficult.  On\nthe one hand, it could be mention of an item \"Neque\", mention of another item \"Porro\",\nand mention of another item \"Quisquam Est\", with just the last one requiring the\nexplanatory paragraph \"Qui dolorem ipsum quia dolor...\"; and then an item \"Ut Enim\".  In\nthat case, you'd want to format it like so:\n\nNeque\n\nPorro\n\nQuisquam Est\nQui dolorem ipsum quia dolor sit amet, consectetur, adipisci\nvelit, sed quia non numquam eius modi tempora incidunt ut\nlabore et dolore magnam aliquam quaerat voluptatem.\n\nUt Enim\n\nBut it could equally well be a discussion of three (related or equivalent) items,\n\"Neque\", \"Porro\", and \"Quisquam Est\", followed by a paragraph explaining them all, and\nthen a new item \"Ut Enim\".  In that case, you'd probably want to format it like so:\n\nNeque\nPorro\nQuisquam Est\nQui dolorem ipsum quia dolor sit amet, consectetur, adipisci\nvelit, sed quia non numquam eius modi tempora incidunt ut\nlabore et dolore magnam aliquam quaerat voluptatem.\n\nUt Enim\n\nBut (for the foreseeable future), Pod does not provide any way for Pod authors to\ndistinguish which grouping is meant by the above \"=item\"-cluster structure.  So\nformatters should format it like so:\n\nNeque\n\nPorro\n\nQuisquam Est\n\nQui dolorem ipsum quia dolor sit amet, consectetur, adipisci\nvelit, sed quia non numquam eius modi tempora incidunt ut\nlabore et dolore magnam aliquam quaerat voluptatem.\n\nUt Enim\n\nThat is, there should be (at least roughly) equal spacing between items as between\nparagraphs (although that spacing may well be less than the full height of a line of\ntext).  This leaves it to the reader to use (con)textual cues to figure out whether the\n\"Qui dolorem ipsum...\" paragraph applies to the \"Quisquam Est\" item or to all three items\n\"Neque\", \"Porro\", and \"Quisquam Est\".  While not an ideal situation, this is preferable\nto providing formatting cues that may be actually contrary to the author's intent.\n"
                    },
                    {
                        "name": "About Data Paragraphs and \"=begin/=end\" Regions",
                        "content": "Data paragraphs are typically used for inlining non-Pod data that is to be used (typically\npassed through) when rendering the document to a specific format:\n\n=begin rtf\n\n\\par{\\pard\\qr\\sa4500{\\i Printed\\~\\chdate\\~\\chtime}\\par}\n\n=end rtf\n\nThe exact same effect could, incidentally, be achieved with a single \"=for\" paragraph:\n\n=for rtf \\par{\\pard\\qr\\sa4500{\\i Printed\\~\\chdate\\~\\chtime}\\par}\n\n(Although that is not formally a data paragraph, it has the same meaning as one, and Pod\nparsers may parse it as one.)\n\nAnother example of a data paragraph:\n\n=begin html\n\nI like <em>PIE</em>!\n\n<hr>Especially pecan pie!\n\n=end html\n\nIf these were ordinary paragraphs, the Pod parser would try to expand the \"E</em>\" (in the\nfirst paragraph) as a formatting code, just like \"E<lt>\" or \"E<eacute>\".  But since this is\nin a \"=begin identifier\"...\"=end identifier\" region and the identifier \"html\" doesn't begin\nhave a \":\" prefix, the contents of this region are stored as data paragraphs, instead of\nbeing processed as ordinary paragraphs (or if they began with a spaces and/or tabs, as\nverbatim paragraphs).\n\nAs a further example: At time of writing, no \"biblio\" identifier is supported, but suppose\nsome processor were written to recognize it as a way of (say) denoting a bibliographic\nreference (necessarily containing formatting codes in ordinary paragraphs).  The fact that\n\"biblio\" paragraphs were meant for ordinary processing would be indicated by prefacing each\n\"biblio\" identifier with a colon:\n\n=begin :biblio\n\nWirth, Niklaus.  1976.  I<Algorithms + Data Structures =\nPrograms.>  Prentice-Hall, Englewood Cliffs, NJ.\n\n=end :biblio\n\nThis would signal to the parser that paragraphs in this begin...end region are subject to\nnormal handling as ordinary/verbatim paragraphs (while still tagged as meant only for\nprocessors that understand the \"biblio\" identifier).  The same effect could be had with:\n\n=for :biblio\nWirth, Niklaus.  1976.  I<Algorithms + Data Structures =\nPrograms.>  Prentice-Hall, Englewood Cliffs, NJ.\n\nThe \":\" on these identifiers means simply \"process this stuff normally, even though the\nresult will be for some special target\".  I suggest that parser APIs report \"biblio\" as the\ntarget identifier, but also report that it had a \":\" prefix.  (And similarly, with the above\n\"html\", report \"html\" as the target identifier, and note the lack of a \":\" prefix.)\n\nNote that a \"=begin identifier\"...\"=end identifier\" region where identifier begins with a\ncolon, can contain commands.  For example:\n\n=begin :biblio\n\nWirth's classic is available in several editions, including:\n\n=for comment\nhm, check abebooks.com for how much used copies cost.\n\n=over\n\n=item\n\nWirth, Niklaus.  1975.  I<Algorithmen und Datenstrukturen.>\nTeubner, Stuttgart.  [Yes, it's in German.]\n\n=item\n\nWirth, Niklaus.  1976.  I<Algorithms + Data Structures =\nPrograms.>  Prentice-Hall, Englewood Cliffs, NJ.\n\n=back\n\n=end :biblio\n\nNote, however, a \"=begin identifier\"...\"=end identifier\" region where identifier does not\nbegin with a colon, should not directly contain \"=head1\" ... \"=head4\" commands, nor \"=over\",\nnor \"=back\", nor \"=item\".  For example, this may be considered invalid:\n\n=begin somedata\n\nThis is a data paragraph.\n\n=head1 Don't do this!\n\nThis is a data paragraph too.\n\n=end somedata\n\nA Pod processor may signal that the above (specifically the \"=head1\" paragraph) is an error.\nNote, however, that the following should not be treated as an error:\n\n=begin somedata\n\nThis is a data paragraph.\n\n=cut\n\n# Yup, this isn't Pod anymore.\nsub excl { (rand() > .5) ? \"hoo!\" : \"hah!\" }\n\n=pod\n\nThis is a data paragraph too.\n\n=end somedata\n\nAnd this too is valid:\n\n=begin someformat\n\nThis is a data paragraph.\n\nAnd this is a data paragraph.\n\n=begin someotherformat\n\nThis is a data paragraph too.\n\nAnd this is a data paragraph too.\n\n=begin :yetanotherformat\n\n=head2 This is a command paragraph!\n\nThis is an ordinary paragraph!\n\nAnd this is a verbatim paragraph!\n\n=end :yetanotherformat\n\n=end someotherformat\n\nAnother data paragraph!\n\n=end someformat\n\nThe contents of the above \"=begin :yetanotherformat\" ...  \"=end :yetanotherformat\" region\naren't data paragraphs, because the immediately containing region's identifier\n(\":yetanotherformat\") begins with a colon.  In practice, most regions that contain data\nparagraphs will contain only data paragraphs; however, the above nesting is syntactically\nvalid as Pod, even if it is rare.  However, the handlers for some formats, like \"html\", will\naccept only data paragraphs, not nested regions; and they may complain if they see (targeted\nfor them) nested regions, or commands, other than \"=end\", \"=pod\", and \"=cut\".\n\nAlso consider this valid structure:\n\n=begin :biblio\n\nWirth's classic is available in several editions, including:\n\n=over\n\n=item\n\nWirth, Niklaus.  1975.  I<Algorithmen und Datenstrukturen.>\nTeubner, Stuttgart.  [Yes, it's in German.]\n\n=item\n\nWirth, Niklaus.  1976.  I<Algorithms + Data Structures =\nPrograms.>  Prentice-Hall, Englewood Cliffs, NJ.\n\n=back\n\nBuy buy buy!\n\n=begin html\n\n<img src='wirthspokesmodelingbook.png'>\n\n<hr>\n\n=end html\n\nNow now now!\n\n=end :biblio\n\nThere, the \"=begin html\"...\"=end html\" region is nested inside the larger \"=begin\n:biblio\"...\"=end :biblio\" region.  Note that the content of the \"=begin html\"...\"=end html\"\nregion is data paragraph(s), because the immediately containing region's identifier (\"html\")\ndoesn't begin with a colon.\n\nPod parsers, when processing a series of data paragraphs one after another (within a single\nregion), should consider them to be one large data paragraph that happens to contain blank\nlines.  So the content of the above \"=begin html\"...\"=end html\" may be stored as two data\nparagraphs (one consisting of \"<img src='wirthspokesmodelingbook.png'>\\n\" and another\nconsisting of \"<hr>\\n\"), but should be stored as a single data paragraph (consisting of \"<img\nsrc='wirthspokesmodelingbook.png'>\\n\\n<hr>\\n\").\n\nPod processors should tolerate empty \"=begin something\"...\"=end something\" regions, empty\n\"=begin :something\"...\"=end :something\" regions, and contentless \"=for something\" and \"=for\n:something\" paragraphs.  I.e., these should be tolerated:\n\n=for html\n\n=begin html\n\n=end html\n\n=begin :biblio\n\n=end :biblio\n\nIncidentally, note that there's no easy way to express a data paragraph starting with\nsomething that looks like a command.  Consider:\n\n=begin stuff\n\n=shazbot\n\n=end stuff\n\nThere, \"=shazbot\" will be parsed as a Pod command \"shazbot\", not as a data paragraph\n\"=shazbot\\n\".  However, you can express a data paragraph consisting of \"=shazbot\\n\" using\nthis code:\n\n=for stuff =shazbot\n\nThe situation where this is necessary, is presumably quite rare.\n\nNote that =end commands must match the currently open =begin command.  That is, they must\nproperly nest.  For example, this is valid:\n\n=begin outer\n\nX\n\n=begin inner\n\nY\n\n=end inner\n\nZ\n\n=end outer\n\nwhile this is invalid:\n\n=begin outer\n\nX\n\n=begin inner\n\nY\n\n=end outer\n\nZ\n\n=end inner\n\nThis latter is improper because when the \"=end outer\" command is seen, the currently open\nregion has the formatname \"inner\", not \"outer\".  (It just happens that \"outer\" is the format\nname of a higher-up region.)  This is an error.  Processors must by default report this as an\nerror, and may halt processing the document containing that error.  A corollary of this is\nthat regions cannot \"overlap\". That is, the latter block above does not represent a region\ncalled \"outer\" which contains X and Y, overlapping a region called \"inner\" which contains Y\nand Z.  But because it is invalid (as all apparently overlapping regions would be), it\ndoesn't represent that, or anything at all.\n\nSimilarly, this is invalid:\n\n=begin thing\n\n=end hting\n\nThis is an error because the region is opened by \"thing\", and the \"=end\" tries to close\n\"hting\" [sic].\n\nThis is also invalid:\n\n=begin thing\n\n=end\n\nThis is invalid because every \"=end\" command must have a formatname parameter.\n"
                    }
                ]
            },
            "SEE ALSO": {
                "content": "perlpod, \"PODs: Embedded Documentation\" in perlsyn, podchecker\n",
                "subsections": []
            },
            "AUTHOR": {
                "content": "Sean M. Burke\n\n\n\nperl v5.34.0                                 2025-07-25                               PERLPODSPEC(1)",
                "subsections": []
            }
        }
    }
}