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ROFF(7)                Miscellaneous Information Manual                ROFF(7)

NAME
     roff -- roff language reference for mandoc

DESCRIPTION
     The roff language is a general purpose text formatting language.  Since
     traditional implementations of the mdoc(7) and man(7) manual formatting
     languages are based on it, many real-world manuals use small numbers of
     roff requests intermixed with their mdoc(7) or man(7) code.  To properly
     format such manuals, the mandoc(1) utility supports a tiny subset of roff
     requests.  Only these requests supported by mandoc(1) are documented in
     the present manual, together with the basic language syntax shared by
     roff, mdoc(7), and man(7).  For complete roff manuals, consult the SEE
     ALSO section.

     Input lines beginning with the control character `.' are parsed for
     requests and macros.  Such lines are called ``request lines'' or ``macro
     lines'', respectively.  Requests change the processing state and
     manipulate the formatting; some macros also define the document structure
     and produce formatted output.  The single quote ("'") is accepted as an
     alternative control character, treated by mandoc(1) just like `.'

     Lines not beginning with control characters are called ``text lines''.
     They provide free-form text to be printed; the formatting of the text
     depends on the respective processing context.

LANGUAGE SYNTAX
     roff documents may contain only graphable 7-bit ASCII characters, the
     space character, and, in certain circumstances, the tab character.  The
     back-space character `\' indicates the start of an escape sequence for
     Comments, Special Characters, Predefined Strings, and user-defined
     strings defined using the ds request.

   Comments
     Text following an escaped double-quote `\"', whether in a request, macro,
     or text line, is ignored to the end of the line.  A request line
     beginning with a control character and comment escape `.\"' is also
     ignored.  Furthermore, request lines with only a control character and
     optional trailing whitespace are stripped from input.

     Examples:
           .\" This is a comment line.
           .\" The next line is ignored:
           .
           .Sh EXAMPLES \" This is a comment, too.
           example text \" And so is this.

   Special Characters
     Special characters are used to encode special glyphs and are rendered
     differently across output media.  They may occur in request, macro, and
     text lines.  Sequences begin with the escape character `\' followed by
     either an open-parenthesis `(' for two-character sequences; an open-
     bracket `[' for n-character sequences (terminated at a close-bracket
     `]'); or a single one character sequence.

     Examples:
           \(em    Two-letter em dash escape.
           \e      One-letter backslash escape.

     See mandoc_char(7) for a complete list.

   Text Decoration
     Terms may be text-decorated using the `\f' escape followed by an
     indicator: B (bold), I (italic), R (regular), or P (revert to previous
     mode).  A numerical representation 3, 2, or 1 (bold, italic, and regular,
     respectively) may be used instead.  The indicator or numerical
     representative may be preceded by C (constant-width), which is ignored.

     Examples:
           \fBbold\fR
                   Write in bold, then switch to regular font mode.
           \fIitalic\fP
                   Write in italic, then return to previous font mode.

     Text decoration is not recommended for mdoc(7), which encourages semantic
     annotation.

   Predefined Strings
     Predefined strings, like Special Characters, mark special output glyphs.
     Predefined strings are escaped with the slash-asterisk, `\*': single-
     character `\*X', two-character `\*(XX', and N-character `\*[N]'.

     Examples:
           \*(Am   Two-letter ampersand predefined string.
           \*q     One-letter double-quote predefined string.

     Predefined strings are not recommended for use, as they differ across
     implementations.  Those supported by mandoc(1) are listed in
     mandoc_char(7).  Manuals using these predefined strings are almost
     certainly not portable.

   Whitespace
     Whitespace consists of the space character.  In text lines, whitespace is
     preserved within a line.  In request and macro lines, whitespace delimits
     arguments and is discarded.

     Unescaped trailing spaces are stripped from text line input unless in a
     literal context.  In general, trailing whitespace on any input line is
     discouraged for reasons of portability.  In the rare case that a blank
     character is needed at the end of an input line, it may be forced by
     `\ \&'.

     Literal space characters can be produced in the output using escape
     sequences.  In macro lines, they can also be included in arguments using
     quotation; see MACRO SYNTAX for details.

     Blank text lines, which may include whitespace, are only permitted within
     literal contexts.  If the first character of a text line is a space, that
     line is printed with a leading newline.

   Scaling Widths
     Many requests and macros support scaled widths for their arguments.  The
     syntax for a scaled width is `[+-]?[0-9]*.[0-9]*[:unit:]', where a
     decimal must be preceded or followed by at least one digit.  Negative
     numbers, while accepted, are truncated to zero.

     The following scaling units are accepted:

           c       centimetre
           i       inch
           P       pica (~1/6 inch)
           p       point (~1/72 inch)
           f       synonym for `u'
           v       default vertical span
           m       width of rendered `m' (em) character
           n       width of rendered `n' (en) character
           u       default horizontal span
           M       mini-em (~1/100 em)

     Using anything other than `m', `n', `u', or `v' is necessarily non-
     portable across output media.  See COMPATIBILITY.

     If a scaling unit is not provided, the numerical value is interpreted
     under the default rules of `v' for vertical spaces and `u' for horizontal
     ones.

     Examples:
           .Bl -tag -width 2i  two-inch tagged list indentation in mdoc(7)
           .HP 2i              two-inch tagged list indentation in man(7)
           .sp 2v              two vertical spaces

   Sentence Spacing
     Each sentence should terminate at the end of an input line.  By doing
     this, a formatter will be able to apply the proper amount of spacing
     after the end of sentence (unescaped) period, exclamation mark, or
     question mark followed by zero or more non-sentence closing delimiters
     (`)', `]', `'', `"').

     The proper spacing is also intelligently preserved if a sentence ends at
     the boundary of a macro line.

     Examples:
           Do not end sentences mid-line like this.  Instead,
           end a sentence like this.
           A macro would end like this:
           .Xr mandoc 1 .

REQUEST SYNTAX
     A request or macro line consists of:

     1.   the control character `.' or `'' at the beginning of the line,
     2.   optionally an arbitrary amount of whitespace,
     3.   the name of the request or the macro, which is one word of arbitrary
          length, terminated by whitespace,
     4.   and zero or more arguments delimited by whitespace.

     Thus, the following request lines are all equivalent:

           .ig end
           .ig    end
           .   ig end

MACRO SYNTAX
     Macros are provided by the mdoc(7) and man(7) languages and can be
     defined by the de request.  When called, they follow the same syntax as
     requests, except that macro arguments may optionally be quoted by
     enclosing them in double quote characters (`"').  Quoted text, even if it
     contains whitespace or would cause a macro invocation when unquoted, is
     always considered literal text.  Inside quoted text, pairs of double
     quote characters (`""') resolve to single double quote characters.

     To be recognised as the beginning of a quoted argument, the opening quote
     character must be preceded by a space character.  A quoted argument
     extends to the next double quote character that is not part of a pair, or
     to the end of the input line, whichever comes earlier.  Leaving out the
     terminating double quote character at the end of the line is discouraged.
     For clarity, if more arguments follow on the same input line, it is
     recommended to follow the terminating double quote character by a space
     character; in case the next character after the terminating double quote
     character is anything else, it is regarded as the beginning of the next,
     unquoted argument.

     Both in quoted and unquoted arguments, pairs of backslashes (`\\')
     resolve to single backslashes.  In unquoted arguments, space characters
     can alternatively be included by preceding them with a backslash (`\ '),
     but quoting is usually better for clarity.

     Examples:
           .Fn strlen "const char *s"
                   Group arguments "const char *s" into one function argument.
                   If unspecified, "const", "char", and "*s" would be
                   considered separate arguments.
           .Op "Fl a"
                   Consider "Fl a" as literal text instead of a flag macro.

REQUEST REFERENCE
     The mandoc(1) roff parser recognises the following requests.  Note that
     the roff language defines many more requests not implemented in
     mandoc(1).

   ad
     Set line adjustment mode.  This line-scoped request is intended to have
     one argument to select normal, left, right, or centre adjustment for
     subsequent text.  Currently, it is ignored including its arguments, and
     the number of arguments is not checked.

   am
     Append to a macro definition.  The syntax of this request is the same as
     that of de.  It is currently ignored by mandoc(1), as are its children.

   ami
     Append to a macro definition, specifying the macro name indirectly.  The
     syntax of this request is the same as that of dei.  It is currently
     ignored by mandoc(1), as are its children.

   am1
     Append to a macro definition, switching roff compatibility mode off
     during macro execution.  The syntax of this request is the same as that
     of de1.  It is currently ignored by mandoc(1), as are its children.

   de
     Define a roff macro.  Its syntax can be either

           .de name
           macro definition
           ..

     or

           .de name end
           macro definition
           .end

     Both forms define or redefine the macro name to represent the macro
     definition, which may consist of one or more input lines, including the
     newline characters terminating each line, optionally containing calls to
     roff requests, roff macros or high-level macros like man(7) or mdoc(7)
     macros, whichever applies to the document in question.

     Specifying a custom end macro works in the same way as for ig; namely,
     the call to `.end' first ends the macro definition, and after that, it is
     also evaluated as a roff request or roff macro, but not as a high-level
     macro.

     The macro can be invoked later using the syntax

           .name [argument [argument ...]]

     Regarding argument parsing, see MACRO SYNTAX above.

     The line invoking the macro will be replaced in the input stream by the
     macro definition, replacing all occurrences of \\$N, where N is a digit,
     by the Nth argument.  For example,

           .de ZN
           \fI\^\\$1\^\fP\\$2
           ..
           .ZN XtFree .

     produces

           \fI\^XtFree\^\fP.

     in the input stream, and thus in the output: XtFree.

     Since macros and user-defined strings share a common string table,
     defining a macro name clobbers the user-defined string name, and the
     macro definition can also be printed using the `\*' string interpolation
     syntax described below ds, but this is rarely useful because every macro
     definition contains at least one explicit newline character.

     In order to prevent endless recursion, both groff and mandoc(1) limit the
     stack depth for expanding macros and strings to a large, but finite
     number.  Do not rely on the exact value of this limit.

   dei
     Define a roff macro, specifying the macro name indirectly.  The syntax of
     this request is the same as that of de.  It is currently ignored by
     mandoc(1), as are its children.

   de1
     Define a roff macro that will be executed with roff compatibility mode
     switched off during macro execution.  This is a GNU extension not
     available in traditional roff implementations and not even in older
     versions of groff.  Since mandoc(1) does not implement roff compatibility
     mode at all, it handles this request as an alias for de.

   ds
     Define a user-defined string.  Its syntax is as follows:

           .ds name ["]string

     The name and string arguments are space-separated.  If the string begins
     with a double-quote character, that character will not be part of the
     string.  All remaining characters on the input line form the string,
     including whitespace and double-quote characters, even trailing ones.

     The string can be interpolated into subsequent text by using \*[name] for
     a name of arbitrary length, or \*(NN or \*N if the length of name is two
     or one characters, respectively.  Interpolation can be prevented by
     escaping the leading backslash; that is, an asterisk preceded by an even
     number of backslashes does not trigger string interpolation.

     Since user-defined strings and macros share a common string table,
     defining a string name clobbers the macro name, and the name used for
     defining a string can also be invoked as a macro, in which case the
     following input line will be appended to the string, forming a new input
     line passed to the roff parser.  For example,

           .ds badidea .S
           .badidea
           H SYNOPSIS

     invokes the SH macro when used in a man(7) document.  Such abuse is of
     course strongly discouraged.

   el
     The "else" half of an if/else conditional.  Pops a result off the stack
     of conditional evaluations pushed by ie and uses it as its conditional.
     If no stack entries are present (e.g., due to no prior ie calls) then
     false is assumed.  The syntax of this request is similar to if except
     that the conditional is missing.

   EN
     End an equation block.  See EQ.

   EQ
     Begin an equation block.  See eqn(7) for a description of the equation
     language.

   hy
     Set automatic hyphenation mode.  This line-scoped request is currently
     ignored.

   ie
     The "if" half of an if/else conditional.  The result of the conditional
     is pushed into a stack used by subsequent invocations of el, which may be
     separated by any intervening input (or not exist at all).  Its syntax is
     equivalent to if.

   if
     Begins a conditional.  Right now, the conditional evaluates to true if
     and only if it starts with the letter n, indicating processing in nroff
     style as opposed to troff style.  If a conditional is false, its children
     are not processed, but are syntactically interpreted to preserve the
     integrity of the input document.  Thus,

           .if t .ig

     will discard the `.ig', which may lead to interesting results, but

           .if t .if t \{\

     will continue to syntactically interpret to the block close of the final
     conditional.  Sub-conditionals, in this case, obviously inherit the truth
     value of the parent.  This request has the following syntax:

           .if COND \{\
           BODY...
           .\}

           .if COND \{ BODY
           BODY... \}

           .if COND \{ BODY
           BODY...
           .\}

           .if COND \
           BODY

     COND is a conditional statement.  roff allows for complicated
     conditionals; mandoc is much simpler.  At this time, mandoc supports only
     `n', evaluating to true; and `t', `e', and `o', evaluating to false.  All
     other invocations are read up to the next end of line or space and
     evaluate as false.

     If the BODY section is begun by an escaped brace `\{', scope continues
     until a closing-brace escape sequence `.\}'.  If the BODY is not enclosed
     in braces, scope continues until the end of the line.  If the COND is
     followed by a BODY on the same line, whether after a brace or not, then
     requests and macros must begin with a control character.  It is generally
     more intuitive, in this case, to write

           .if COND \{\
           .foo
           bar
           .\}

     than having the request or macro follow as

           .if COND \{ .foo

     The scope of a conditional is always parsed, but only executed if the
     conditional evaluates to true.

     Note that the `\}' is converted into a zero-width escape sequence if not
     passed as a standalone macro `.\}'.  For example,

           .Fl a \} b

     will result in `\}' being considered an argument of the `Fl' macro.

   ig
     Ignore input.  Its syntax can be either

           .ig
           ignored text
           ..

     or

           .ig end
           ignored text
           .end

     In the first case, input is ignored until a `..' request is encountered
     on its own line.  In the second case, input is ignored until the
     specified `.end' macro is encountered.  Do not use the escape character
     `\' anywhere in the definition of end; it would cause very strange
     behaviour.

     When the end macro is a roff request or a roff macro, like in

           .ig if

     the subsequent invocation of if will first terminate the ignored text,
     then be invoked as usual.  Otherwise, it only terminates the ignored
     text, and arguments following it or the `..' request are discarded.

   ne
     Declare the need for the specified minimum vertical space before the next
     trap or the bottom of the page.  This line-scoped request is currently
     ignored.

   nh
     Turn off automatic hyphenation mode.  This line-scoped request is
     currently ignored.

   rm
     Remove a request, macro or string.  This request is intended to have one
     argument, the name of the request, macro or string to be undefined.
     Currently, it is ignored including its arguments, and the number of
     arguments is not checked.

   nr
     Define a register.  A register is an arbitrary string value that defines
     some sort of state, which influences parsing and/or formatting.  Its
     syntax is as follows:

           .nr name value

     The value may, at the moment, only be an integer.  So far, only the
     following register name is recognised:

     nS      If set to a positive integer value, certain mdoc(7) macros will
             behave in the same way as in the SYNOPSIS section.  If set to 0,
             these macros will behave in the same way as outside the SYNOPSIS
             section, even when called within the SYNOPSIS section itself.
             Note that starting a new mdoc(7) section with the Sh macro will
             reset this register.

   ns
     Turn on no-space mode.  This line-scoped request is intended to take no
     arguments.  Currently, it is ignored including its arguments, and the
     number of arguments is not checked.

   ps
     Change point size.  This line-scoped request is intended to take one
     numerical argument.  Currently, it is ignored including its arguments,
     and the number of arguments is not checked.

   so
     Include a source file.  Its syntax is as follows:

           .so file

     The file will be read and its contents processed as input in place of the
     `.so' request line.  To avoid inadvertent inclusion of unrelated files,
     mandoc(1) only accepts relative paths not containing the strings "../"
     and "/..".

     This request requires man(1) to change to the right directory before
     calling mandoc(1), per convention to the root of the manual tree.
     Typical usage looks like:

           .so man3/Xcursor.3

     As the whole concept is rather fragile, the use of so is discouraged.
     Use ln(1) instead.

   ta
     Set tab stops.  This line-scoped request can take an arbitrary number of
     arguments.  Currently, it is ignored including its arguments.

   tr
     Output character translation.  Its syntax is as follows:

           .tr [ab]+

     Pairs of ab characters are replaced (a for b).  Replacement (or origin)
     characters may also be character escapes; thus,

           tr \(xx\(yy

     replaces all invocations of \(xx with \(yy.

   T&&
     Re-start a table layout, retaining the options of the prior table
     invocation.  See TS.

   TE
     End a table context.  See TS.

   TS
     Begin a table, which formats input in aligned rows and columns.  See
     tbl(7) for a description of the tbl language.

COMPATIBILITY
     This section documents compatibility between mandoc and other other roff
     implementations, at this time limited to GNU troff ("groff").  The term
     "historic groff" refers to groff version 1.15.

     -   In mandoc, the EQ, TE, TS, and T&, macros are considered regular
         macros.  In all other roff implementations, these are special macros
         that must be specified without spacing between the control character
         (which must be a period) and the macro name.
     -   The nS register is only compatible with OpenBSD's groff-1.15.
     -   Historic groff did not accept white-space before a custom end macro
         for the ig request.
     -   The if and family would print funny white-spaces with historic groff
         when using the next-line syntax.

SEE ALSO
     mandoc(1), eqn(7), man(7), mandoc_char(7), mdoc(7), tbl(7)

     Joseph F. Ossanna and Brian W. Kernighan, Troff User's Manual, AT&T Bell
     Laboratories, Computing Science Technical Report, 54, 1976 and 1992,
     Murray Hill, New Jersey, http://www.kohala.com/start/troff/cstr54.ps.

     Joseph F. Ossanna, Brian W. Kernighan, and Gunnar Ritter, Heirloom
     Documentation Tools Nroff/Troff User's Manual, September 17, 2007,
     http://heirloom.sourceforge.net/doctools/troff.pdf.

HISTORY
     The RUNOFF typesetting system, whose input forms the basis for roff, was
     written in MAD and FAP for the CTSS operating system by Jerome E.
     Saltzer in 1964.  Doug McIlroy rewrote it in BCPL in 1969, renaming it
     roff.  Dennis M. Ritchie rewrote McIlroy's roff in PDP-11 assembly for
     Version 1 AT&T UNIX, Joseph F. Ossanna improved roff and renamed it nroff
     for Version 2 AT&T UNIX, then ported nroff to C as troff, which Brian W.
     Kernighan released with Version 7 AT&T UNIX.  In 1989, James Clarke re-
     implemented troff in C++, naming it groff.

AUTHORS
     This roff reference was written by Kristaps Dzonsons, kristaps@bsd.lv;
     and Ingo Schwarze, schwarze@openbsd.org.

NetBSD 6.1.5                   December 11, 2011                  NetBSD 6.1.5