Lint-check (removed unused variable).

[mandoc.git] / mdoc.7

.\"     $Id: mdoc.7,v 1.44 2009/07/17 12:08:08 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 17 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 INPUT ENCODING
.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 termination.  
.\" 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 1
for a complete list.  Examples include 
.Sq \e(em 
.Pq em-dash 
and 
.Sq \ee
.Pq back-slash .
.\" PARAGRAPH------------
.Pp
An alternative escape sequence is
the slash-asterisk,
.Sq \e* ,
but this method is discouraged for compatibility reasons.
.\" PARAGRAPH------------
.Pp
Terms may
also 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.
.\" SUB-SECTION----------------------
.Ss Whitespace
In general, consecutive blocks of whitespace are pruned from input.
These are later re-added, when applicable, by 
.Xr mandoc 1 .
.\" PARAGRAPH------------
.Pp
Blank lines are permitted within
.Sq \&Bd \-literal
or
.Sq \&Bd \-unfilled
contexts.  Tab characters are only acceptable when delimiting 
.Sq \&Bl \-column
and in
.Sq \&Bd \-literal
or
.Sq \&Bd \-unfilled
contexts.
.\" SECTION---------------------------------------------
.Sh MANUAL STRUCTURE
Each
.Nm
document must begin with a document prologue, containing, in order, 
.Sq \&Dd ,
.Sq \&Dt ,
and
.Sq \&Os 
(using this manual as an example):
.Bd -literal -offset indent
\&.Dd $\&Mdocdate$
\&.Dt mdoc 7
\&.Os
\&.Sh NAME
\&.Nm mdoc
\&.Nd mdoc language reference
.Ed
.Pp
Following these, the document body must begin with the NAME section
containing at least one 
.Sq \&Nm
followed by 
.Sq \&Nd .
.\" 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 semantic annotations.
.\" PARAGRAPH------------
.Pp
The syntax of 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 
.Qq 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    \&No     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
.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
Some character sequences in groff are not handled depending on escape
style, e.g., 
.Sq \e(ba
and
.Sq \e*(Ba
may not be interchanged.  This is no longer the case: all character
sequences resolve to the same symbol, regardless the escape style.
.\" 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
If an special-character control character is escaped
.Sq \e\e ,
it will obviously not render the subsequent sequence.  Even newer
versions of groff seem to dither on this.
.\" 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
utility 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 arguments to 
.Sq \&.An
are inane.
.El