Clarified special chars/predefined chars in mandoc_char.7.

[mandoc.git] / mdoc.7

.\"     $Id: mdoc.7,v 1.54 2009/07/27 12:35:54 kristaps Exp $
.\"
.\" Copyright (c) 2009 Kristaps Dzonsons <kristaps@kth.se>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: July 27 2009 $
.Dt MDOC 7
.Os
.\" SECTION---------------------------------------------
.Sh NAME
.Nm mdoc
.Nd mdoc language reference
.\" SECTION---------------------------------------------
.Sh DESCRIPTION
The
.Nm mdoc
language is used to format
.Bx
.Ux
manuals.  In this reference document, we describe its syntax, structure,
and usage.  Our reference implementation is
.Xr mandoc 1 .
The
.Sx COMPATIBILITY
section describes compatibility with
.Xr groff 1 .
.\" PARAGRAPH------------
.Pp
An
.Nm
document follows simple rules:  lines beginning with the control
character
.Sq \.
are parsed for macros.  Other lines are interpreted within the scope of
prior macros:
.Bd -literal -offset indent
\&.Sh Macro lines change control state.
Other lines are interpreted within the current state.
.Ed
.\" SECTION---------------------------------------------
.Sh LANGUAGE SYNTAX
.Nm
documents may contain only graphable 7-bit ASCII characters, the space
character, and, in certain circumstances, the tab character.  All
manuals must have
.Ux
line terminators.
.\" SUB-SECTION----------------------
.Ss Comments
Text following a
.Sq \e" ,
whether in a macro or free-form text line, is ignored to the end of
line.  A macro line with only a control character and comment escape,
.Sq \&.\e" ,
is also ignored.
.\" SUB-SECTION----------------------
.Ss Reserved Characters
Within a macro line, the following characters are reserved:
.Bl -tag -width Ds -offset indent -compact
.It \&.
.Pq period
.It \&,
.Pq comma
.It \&:
.Pq colon
.It \&;
.Pq semicolon
.It \&(
.Pq left-parenthesis
.It \&)
.Pq right-parenthesis
.It \&[
.Pq left-bracket
.It \&]
.Pq right-bracket
.It \&?
.Pq question
.It \&!
.Pq exclamation
.It \&|
.Pq vertical bar
.El
.\" PARAGRAPH------------
.Pp
Use of reserved characters is described in
.Sx MACRO SYNTAX .
For general use in macro lines, these characters must either be escaped
with a non-breaking space
.Pq Sq \e&
or, if applicable, an appropriate escape sequence used.
.\" SUB-SECTION----------------------
.Ss Special Characters
Special characters may occur in both macro and free-form lines.
Sequences begin with the escape character
.Sq \e
followed by either an open-parenthesis
.Sq \&(
for two-character sequences; an open-bracket
.Sq \&[
for n-character sequences (terminated at a close-bracket
.Sq \&] ) ;
or a single one-character sequence.  See
.Xr mandoc_char 7
for a complete list.  Examples include
.Sq \e(em
.Pq em-dash
and
.Sq \ee
.Pq back-slash .
.\" SUB-SECTION----------------------
.Ss Text Decoration
Terms may be text-decorated using the
.Sq \ef
escape followed by an indicator: B (bold), I, (italic), or P and R
(Roman, or reset).  This form is not recommended for 
.Nm ,
which encourages semantic, not presentation, annotation.
.\" SUB-SECTION----------------------
.Ss Predefined Strings
Historically, 
.Xr groff 1
also defined a set of package-specific 
.Dq predefined strings ,
which, like 
.Sx Special Characters ,
demark special output characters and strings by way of input codes.
Predefined strings are escaped with the slash-asterisk,
.Sq \e* :
single-character
.Sq \e*X ,
two-character
.Sq \e*(XX ,
and N-character
.Sq \e*[N] .
See
.Xr mandoc_char 7
for a complete list.  Examples include
.Sq \e*(Am
.Pq ampersand
and
.Sq \e*(Ba
.Pq vertical bar .
.\" SUB-SECTION----------------------
.Ss Whitespace
In non-literal free-form lines, consecutive blocks of whitespace are
pruned from input and added later in the output filter, if applicable:
.Bd -literal -offset indent
These     spaces   are    pruned       from    input.
\&.Bd \-literal
These         are              not.
\&.Ed
.Ed
.\" PARAGRAPH------------
.Pp
In macro lines, whitespace delimits arguments and is discarded.  If
arguments are quoted, whitespace within the quotes is retained.
.\" PARAGRAPH------------
.Pp
Blank lines are only permitted within literal contexts, as are lines
containing only whitespace.  Tab characters are only acceptable when
delimiting
.Sq \&Bl \-column
or when in a literal context.
.\" SUB-SECTION----------------------
.Ss Quotation
Macro arguments may be quoted with a double-quote to group
space-delimited terms or to retain blocks of whitespace.  A quoted
argument begins with a double-quote preceded by whitespace.  The next
double-quote not pair-wise adjacent to another double-quote terminates
the literal, regardless of surrounding whitespace.
.\" PARAGRAPH------------
.Pp
This produces tokens
.Sq a" ,
.Sq b c ,
.Sq de ,
and
.Sq fg" .
Note that any quoted term, be it argument or macro, is indiscriminately
considered literal text.  Thus, the following produces
.Sq \&Em a :
.Bd -literal -offset indent
\&.Em "Em a"
.Ed
.\" PARAGRAPH------------
.Pp
In free-form mode, quotes are regarded as opaque text.
.\" SECTION---------------------------------------------
.Sh MANUAL STRUCTURE
Each
.Nm
document must begin with a document prologue, containing, in order,
.Sq \&Dd ,
.Sq \&Dt ,
and
.Sq \&Os ,
then the NAME section containing at least one
.Sq \&Nm
followed by
.Sq \&Nd :
.Bd -literal -offset indent
\&.Dd $\&Mdocdate$
\&.Dt mdoc 7
\&.Os
\&.Sh NAME
\&.Nm mdoc
\&.Nd mdoc language reference
.Ed
.\" PARAGRAPH------------
.Pp
Subsequent SYNOPSIS and DESCRIPTION sections are strongly encouraged,
but non-compulsory.
.\" SECTION---------------------------------------------
.Sh MACRO SYNTAX
Every line beginning with the control character
.Sq \.
is processed for macros, two- or three-character sequences.
.\" PARAGRAPH------------
.Pp
The syntax of a macro depends on its classification.  In this section,
.Sq \-arg
refers to macro arguments, which may be followed by zero or more
.Sq parm
parameters;
.Sq \&Yo
opens the scope of a macro; and if specified,
.Sq \&Yc
closes it out.
.\" PARAGRAPH------------
.Pp
The
.Em Callable
column indicates that the macro may be called subsequent to the initial
line-macro.  The
.Em Parsable
column indicates whether the macro may be followed by further
(ostensibly callable) macros.  The
.Em Scope
column, if applicable, describes closure rules.
.\" SUB-SECTION----------------------
.Ss Block full-explicit
Multi-line scope closed by an explicit closing macro.  All macros
contains bodies; only
.Pq Sq \&Bf
contains a head.
.Bd -literal -offset indent
\&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead...\(rB
\(lBbody...\(rB
\&.Yc
.Ed
.\" PARAGRAPH------------
.Pp
.Bl -column -compact -offset indent "MacroX" "CallableX" "ParsableX" "closed by XXX"
.It Em Macro Ta Em Callable Ta Em Parsable Ta Em Scope
.It \&Bd     Ta    \&No     Ta    \&No     Ta    closed by \&Ed
.It \&Bf     Ta    \&No     Ta    \&No     Ta    closed by \&Ef
.It \&Bk     Ta    \&No     Ta    \&No     Ta    closed by \&Ek
.It \&Bl     Ta    \&No     Ta    \&No     Ta    closed by \&El
.It \&Ed     Ta    \&No     Ta    \&No     Ta    opened by \&Bd
.It \&Ef     Ta    \&No     Ta    \&No     Ta    opened by \&Bf
.It \&Ek     Ta    \&No     Ta    \&No     Ta    opened by \&Bk
.It \&El     Ta    \&No     Ta    \&No     Ta    opened by \&Bl
.El
.\" SUB-SECTION----------------------
.Ss Block full-implicit
Multi-line scope closed by end-of-file or implicitly by another macro.
All macros have bodies; some
.Po
.Sq \&It \-bullet ,
.Sq \-hyphen ,
.Sq \-dash ,
.Sq \-enum ,
.Sq \-item
.Pc
don't have heads, while
.Sq \&It \-column
may have multiple heads.
.Bd -literal -offset indent
\&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead... \(lBTa head...\(rB\(rB
\(lBbody...\(rB
.Ed
.\" PARAGRAPH------------
.Pp
.Bl -column -compact -offset indent "MacroX" "CallableX" "ParsableX" "closed by XXXXXXXXXXX"
.It Em Macro Ta Em Callable Ta Em Parsable Ta Em Scope
.It \&It     Ta    \&No     Ta    Yes      Ta    closed by \&It, \&El
.It \&Nd     Ta    \&No     Ta    \&No     Ta    closed by \&Sh
.It \&Sh     Ta    \&No     Ta    \&No     Ta    closed by \&Sh
.It \&Ss     Ta    \&No     Ta    \&No     Ta    closed by \&Sh, \&Ss
.El
.\" SUB-SECTION----------------------
.Ss Block partial-explicit
Like block full-explicit, but also with single-line scope.  Each
has at least a body and, in limited circumstances, a head
.Pq So \&Fo Sc , So \&Eo Sc
and/or tail
.Pq So \&Ec Sc .
.Bd -literal -offset indent
\&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead...\(rB
\(lBbody...\(rB
\&.Yc \(lBtail...\(rB

\&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead...\(rB \
\(lBbody...\(rB \&Yc \(lBtail...\(rB
.Ed
.\" PARAGRAPH------------
.Pp
.Bl -column "MacroX" "CallableX" "ParsableX" "closed by XXXX" -compact -offset indent
.It Em Macro Ta Em Callable Ta Em Parsable Ta Em Scope
.It \&Ac     Ta    Yes      Ta    Yes      Ta    opened by \&Ao
.It \&Ao     Ta    Yes      Ta    Yes      Ta    closed by \&Ac
.It \&Bc     Ta    Yes      Ta    Yes      Ta    closed by \&Bo
.It \&Bo     Ta    Yes      Ta    Yes      Ta    opened by \&Bc
.It \&Brc    Ta    Yes      Ta    Yes      Ta    opened by \&Bro
.It \&Bro    Ta    Yes      Ta    Yes      Ta    closed by \&Brc
.It \&Dc     Ta    Yes      Ta    Yes      Ta    opened by \&Do
.It \&Do     Ta    Yes      Ta    Yes      Ta    closed by \&Dc
.It \&Ec     Ta    Yes      Ta    Yes      Ta    opened by \&Eo
.It \&Eo     Ta    Yes      Ta    Yes      Ta    closed by \&Ec
.It \&Fc     Ta    Yes      Ta    Yes      Ta    opened by \&Fo
.It \&Fo     Ta    \&No     Ta    \&No     Ta    closed by \&Fc
.It \&Oc     Ta    Yes      Ta    Yes      Ta    closed by \&Oo
.It \&Oo     Ta    Yes      Ta    Yes      Ta    opened by \&Oc
.It \&Pc     Ta    Yes      Ta    Yes      Ta    closed by \&Po
.It \&Po     Ta    Yes      Ta    Yes      Ta    opened by \&Pc
.It \&Qc     Ta    Yes      Ta    Yes      Ta    opened by \&Oo
.It \&Qo     Ta    Yes      Ta    Yes      Ta    closed by \&Oc
.It \&Re     Ta    \&No     Ta    \&No     Ta    opened by \&Rs
.It \&Rs     Ta    \&No     Ta    \&No     Ta    closed by \&Re
.It \&Sc     Ta    Yes      Ta    Yes      Ta    opened by \&So
.It \&So     Ta    Yes      Ta    Yes      Ta    closed by \&Sc
.It \&Xc     Ta    Yes      Ta    Yes      Ta    opened by \&Xo
.It \&Xo     Ta    Yes      Ta    Yes      Ta    closed by \&Xc
.El
.\" SUB-SECTION----------------------
.Ss Block partial-implicit
Like block full-implicit, but with single-line scope closed by
.Sx Reserved Characters
or end of line.
.Bd -literal -offset indent
\&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBbody...\(rB \(lBres...\(rB
.Ed
.\" PARAGRAPH------------
.Pp
.Bl -column "MacroX" "CallableX" "ParsableX" -compact -offset indent
.It Em Macro Ta Em Callable Ta Em Parsable
.It \&Aq     Ta    Yes      Ta    Yes
.It \&Bq     Ta    Yes      Ta    Yes
.It \&Brq    Ta    Yes      Ta    Yes
.It \&D1     Ta    \&No     Ta    \&Yes
.It \&Dl     Ta    \&No     Ta    Yes
.It \&Dq     Ta    Yes      Ta    Yes
.It \&Op     Ta    Yes      Ta    Yes
.It \&Pq     Ta    Yes      Ta    Yes
.It \&Ql     Ta    Yes      Ta    Yes
.It \&Qq     Ta    Yes      Ta    Yes
.It \&Sq     Ta    Yes      Ta    Yes
.El
.\" SUB-SECTION----------------------
.Ss In-line
Closed by
.Sx Reserved Characters ,
end of line, fixed argument lengths, and/or subsequent macros.  In-line
macros have only text children.  If a number (or inequality) of
arguments is
.Pq n ,
then the macro accepts an arbitrary number of arguments.
.Bd -literal -offset indent
\&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBargs...\(rB \(lbres...\(rb

\&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBargs...\(rB Yc...

\&.Yo \(lB\-arg \(lBval...\(rB\(rB arg0 arg1 argN
.Ed
.\" PARAGRAPH------------
.Pp
.Bl -column "MacroX" "CallableX" "ParsableX" "Arguments" -compact -offset indent
.It Em Macro Ta Em Callable Ta Em Parsable Ta Em Arguments
.It \&%A     Ta    \&No     Ta    \&No     Ta    >0
.It \&%B     Ta    \&No     Ta    \&No     Ta    >0
.It \&%C     Ta    \&No     Ta    \&No     Ta    >0
.It \&%D     Ta    \&No     Ta    \&No     Ta    >0
.It \&%I     Ta    \&No     Ta    \&No     Ta    >0
.It \&%J     Ta    \&No     Ta    \&No     Ta    >0
.It \&%N     Ta    \&No     Ta    \&No     Ta    >0
.It \&%O     Ta    \&No     Ta    \&No     Ta    >0
.It \&%P     Ta    \&No     Ta    \&No     Ta    >0
.It \&%R     Ta    \&No     Ta    \&No     Ta    >0
.It \&%T     Ta    \&No     Ta    \&No     Ta    >0
.It \&%V     Ta    \&No     Ta    \&No     Ta    >0
.It \&Ad     Ta    Yes      Ta    Yes      Ta    n
.It \&An     Ta    Yes      Ta    Yes      Ta    n
.It \&Ap     Ta    Yes      Ta    Yes      Ta    0
.It \&Ar     Ta    Yes      Ta    Yes      Ta    n
.It \&At     Ta    Yes      Ta    Yes      Ta    1
.It \&Bsx    Ta    Yes      Ta    Yes      Ta    n
.It \&Bt     Ta    \&No     Ta    \&No     Ta    0
.It \&Bx     Ta    Yes      Ta    Yes      Ta    n
.It \&Cd     Ta    Yes      Ta    Yes      Ta    >0
.It \&Cm     Ta    Yes      Ta    Yes      Ta    n
.It \&Db     Ta    \&No     Ta    \&No     Ta    1
.It \&Dd     Ta    \&No     Ta    \&No     Ta    >0
.It \&Dt     Ta    \&No     Ta    \&No     Ta    n
.It \&Dv     Ta    Yes      Ta    Yes      Ta    n
.It \&Dx     Ta    Yes      Ta    Yes      Ta    n
.It \&Em     Ta    Yes      Ta    Yes      Ta    >0
.It \&En     Ta    \&No     Ta    \&No     Ta    0
.It \&Er     Ta    Yes      Ta    Yes      Ta    >0
.It \&Es     Ta    \&No     Ta    \&No     Ta    0
.It \&Ev     Ta    Yes      Ta    Yes      Ta    n
.It \&Ex     Ta    \&No     Ta    \&No     Ta    0
.It \&Fa     Ta    Yes      Ta    Yes      Ta    n
.It \&Fd     Ta    \&No     Ta    \&No     Ta    >0
.It \&Fl     Ta    Yes      Ta    Yes      Ta    n
.It \&Fn     Ta    Yes      Ta    Yes      Ta    >0
.It \&Fr     Ta    \&No     Ta    \&No     Ta    n
.It \&Ft     Ta    Yes      Ta    Yes      Ta    n
.It \&Fx     Ta    Yes      Ta    Yes      Ta    n
.It \&Hf     Ta    \&No     Ta    \&No     Ta    n
.It \&Ic     Ta    Yes      Ta    Yes      Ta    >0
.It \&In     Ta    \&No     Ta    \&No     Ta    n
.It \&Lb     Ta    \&No     Ta    \&No     Ta    1
.It \&Li     Ta    Yes      Ta    Yes      Ta    n
.It \&Lk     Ta    Yes      Ta    Yes      Ta    n
.It \&Lp     Ta    \&No     Ta    \&No     Ta    0
.It \&Ms     Ta    Yes      Ta    Yes      Ta    >0
.It \&Mt     Ta    Yes      Ta    Yes      Ta    >0
.It \&Nm     Ta    Yes      Ta    Yes      Ta    n
.It \&No     Ta    Yes      Ta    Yes      Ta    0
.It \&Ns     Ta    Yes      Ta    Yes      Ta    0
.It \&Nx     Ta    Yes      Ta    Yes      Ta    n
.It \&Os     Ta    \&No     Ta    \&No     Ta    n
.It \&Ot     Ta    \&No     Ta    \&No     Ta    n
.It \&Ox     Ta    Yes      Ta    Yes      Ta    n
.It \&Pa     Ta    Yes      Ta    Yes      Ta    n
.It \&Pf     Ta    \&No     Ta    Yes      Ta    1
.It \&Pp     Ta    \&No     Ta    \&No     Ta    0
.It \&Rv     Ta    \&No     Ta    \&No     Ta    0
.It \&Sm     Ta    \&No     Ta    \&No     Ta    1
.It \&St     Ta    \&No     Ta    Yes      Ta    1
.It \&Sx     Ta    Yes      Ta    Yes      Ta    >0
.It \&Sy     Ta    Yes      Ta    Yes      Ta    >0
.It \&Tn     Ta    Yes      Ta    Yes      Ta    >0
.It \&Ud     Ta    \&No     Ta    \&No     Ta    0
.It \&Ux     Ta    Yes      Ta    Yes      Ta    n
.It \&Va     Ta    Yes      Ta    Yes      Ta    n
.It \&Vt     Ta    Yes      Ta    Yes      Ta    >0
.It \&Xr     Ta    Yes      Ta    Yes      Ta    >0, <3
.It \&br     Ta    \&No     Ta    \&No     Ta    0
.It \&sp     Ta    \&No     Ta    \&No     Ta    1
.El
.\" SECTION---------------------------------------------
.Sh COMPATIBILITY
This section documents compatibility with other roff implementations, at
this time limited to
.Xr groff 1 .
The term
.Qq historic groff
refers to those versions before the
.Pa doc.tmac
file re-write
.Pq somewhere between 1.15 and 1.19 .
.\" PARAGRAPH------------
.Pp
.Bl -dash -compact
.\" LIST-ITEM
.It
The
.Sq \-split
or
.Sq \-nosplit
argument to 
.Sq \&An
applies to the whole document, not just to the current section as it
does in groff.
.\" LIST-ITEM
.It
In quoted literals, groff allowed pair-wise double-quotes to produce a
standalone double-quote in formatted output.  This idiosyncratic
behaviour is no longer applicable.
.\" LIST-ITEM
.It
The
.Sq \&sp
macro does not accept negative numbers.
.\" LIST-ITEM
.It
Blocks of whitespace are stripped from both macro and free-form text
lines (except when in literal mode), while groff would retain whitespace
in free-form text lines.
.\" LIST-ITEM
.It
Historic groff has many un-callable macros.  Most of these (excluding
some block-level macros) are now callable, conforming to the
non-historic groff version.
.\" LIST-ITEM
.It
The vertical bar
.Sq \(ba
made historic groff
.Qq go orbital
but is a proper delimiter in this implementation.
.\" LIST-ITEM
.It
.Sq \&It \-nested
is assumed for all lists (it wasn't in historic groff): any list may be
nested and
.Sq \-enum
lists will restart the sequence only for the sub-list.
.\" LIST-ITEM
.It
.Sq \&It \-column
syntax where column widths may be preceded by other arguments (instead
of proceeded) is not supported.
.\" LIST-ITEM
.It
The
.Sq \&At
macro only accepts a single parameter.
.\" LIST-ITEM
.It
Some manuals use
.Sq \&Li
incorrectly by following it with a reserved character and expecting the
delimiter to render.  This is not supported.
.\" LIST-ITEM
.It
In groff, the
.Sq \&Fo
macro only produces the first parameter.  This is no longer the case.
.El
.\" SECTION---------------------------------------------
.Sh SEE ALSO
.Xr mandoc 1 ,
.Xr mandoc_char 7
.\" SECTION---------------------------------------------
.Sh AUTHORS
The
.Nm
reference was written by
.An Kristaps Dzonsons Aq kristaps@kth.se .
.\" SECTION---------------------------------------------
.Sh CAVEATS
There are many ambiguous parts of mdoc.
.\" PARAGRAPH------------
.Pp
.Bl -dash -compact
.\" LIST-ITEM
.It
.Sq \&Fa
should be
.Sq \&Va
as function arguments are variables.
.\" LIST-ITEM
.It
.Sq \&Ft
should be
.Sq \&Vt
as function return types are still types.  Furthermore, the
.Sq \&Ft
should be removed and
.Sq \&Fo ,
which ostensibly follows it, should follow the same convention as
.Sq \&Va .
.\" LIST-ITEM
.It
.Sq \&Va
should formalise that only one or two arguments are acceptable: a
variable name and optional, preceding type.
.\" LIST-ITEM
.It
.Sq \&Fd
is ambiguous.  It's commonly used to indicate an include file in the
synopsis section.
.Sq \&In
should be used, instead.
.\" LIST-ITEM
.It
Only the
.Sq \-literal
argument to
.Sq \&Bd
makes sense.  The remaining ones should be removed.
.\" LIST-ITEM
.It
The
.Sq \&Xo
and
.Sq \&Xc
macros should be deprecated.
.\" LIST-ITEM
.It
The
.Sq \&Dt
macro lacks clarity.  It should be absolutely clear which title will
render when formatting the manual page.
.\" LIST-ITEM
.It
A
.Sq \&Lx
should be provided for Linux (\(`a la
.Sq \&Ox ,
.Sq \&Nx
etc.).
.\" LIST-ITEM
.It
There's no way to refer to references in
.Sq \&Rs/Re
blocks.
.\" LIST-ITEM
.It
The \-split and \-nosplit dictates via
.Sq \&An
are re-set when entering and leaving the AUTHORS section.
.El