.\" $Id$
.\"
.\" 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 $Mdocdate$
.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 the syntax and
structure of the
.Nm
language. 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 XXX
\&.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
.Sq \ ,
and, in certain circumstances, the tab character
.Sq \et .
All manuals must have
.Sq \en
line termination.
.Pp
The only time a blank line is acceptable is within
the context of
.Sq \&.Bd \-literal
or
.Sq \&.Bd \-unfilled .
.Pp
Tab characters
.Pq \et
are only acceptable when delimiting
.Sq \&.Bl \-column
and in
.Sq \&.Bd \-literal
or
.Sq \&.Bd \-unfilled
contexts.
.\" SUB-SECTION
.Ss Comments
Anything following a
.Sq \e"
delimiter is considered a comment (unless the
.Sq \e
itself has been escaped) and is ignored to the end of line.
Furthermore, a macro line with only a control character
.Sq \. ,
optionally followed by whitespace, is ignored.
.\" SUB-SECTION
.Ss Reserved Characters
Within a macro line, the following characters are reserved:
.Bl -tag -width Ds -offset XXXX -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 Closure .
For general non-reserved use, 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 character 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.
.Pp
Characters may alternatively be escaped by a slash-asterisk,
.Sq \e* ,
with the same combinations as described above.
.Pp
Terms may also be text-decorated using the
.Sq \ef
escape followed by a text-decoration letter: B (bold), I, (italic), or P
and R (Roman, or reset). This form is not recommended.
.\" SUB-SECTION
.Ss Whitespace
Unless in literal mode or specifically escaped, consecutive blocks of
whitespace are pruned from input. These are later re-added, if
applicable, by a front-end utility such as
.Xr mandoc 1 .
.\" SECTION
.Sh STRUCTURE
Each
.Nm
document must begin with the document prologue, containing, in order,
.Sq \&.Dd ,
.Sq \&.Dt ,
and
.Sq \&.Os .
Following these, the document body must begin with the NAME section
containing at least one
.Sq \&.Nm
followed by a
.Sq \&.Nd
macro.
.Pp
At least one free-form or macro line must follow this prologue.
.\"
.Ss Classification
Macros are classified by their scope rules. Some macros are allowed to
deviate from their classifications to preserve backward-compatibility
with old macro combinations still found in the manual corpus. These are
specifically noted on a per-macro basis.
.\" SUB-SECTION
.Ss Scope
.Bl -inset
.\" LIST-ITEM
.It Em Block
macros enclose other block macros, in-line macros or text, and
may span multiple lines.
.Bl -inset -offset XXXX
.\" LIST-ITEM
.It Em Full-block
macros always span multiple lines. They consist of zero or
more
.Qq heads ,
subsequent macros or text on the same line following invocation; an
optional
.Qq body ,
which spans subsequent lines of text or macros; and an optional
.Qq tail ,
macros or text on the same line following closure.
.\" LIST-ITEM
.It Em Partial-block
macros may span multiple lines. They consists of a optional
.Qq head ,
text immediately following invocation; always a
.Qq body ,
text or macros following the head on the same and subsequent lines; and
optionally a
.Qq tail ,
text immediately following closure.
.\" LIST-ITEM
.It Em In-line
macros may only enclose text and span at most a single line.
.El
.El
.\" SUB-SECTION
.Ss Closure
Closure of a macro's scope depends first on its classification, then
on whether it's parsable. In this table,
.Sq BFE
refers to block full-explicit and so on.
.\" PARAGRAPH
.Pp
.Bl -tag -width 12n -offset XXXX -compact
.It BPE , BFE
corresponding explicit closure macro
.It BFI
end-of-file or a corresponding implicit closure macro
.It BPI
end-of-line (body may be closed by >0 space-separated
.Sx Reserved Characters ,
although block scope will still be open)
.It INL
end-of-line
.El
.\" PARAGRAPH
.Pp
If a macro (block or in-line) is parsable, it may also be closed out by
one of the following scenarios (unless specifically noted otherwise):
.\" PARAGRAPH
.Pp
.Bl -dash -offset XXXX -compact
.It
a sequence of >0 space-separated
.Sx Reserved Characters ,
.It
another macro,
.It
end-of-line, or
.It
completion of a set number of arguments.
.El
.\" PARAGRAPH
.Pp
If >0 space-separated
.Sx Reserved Characters
are followed by non-reserved characters, the behaviour differs per
macro. In general, scope of the macro is closed and re-opened:
subsequent tokens are interpreted as if the scope had just been opened.
In other circumstances, scope is simply closed out.
.\" SECTION
.Sh SYNTAX
Macros are two or three characters in length. The syntax of macro
invocation depends on its classification.
.Qq \-arg
refers to the macro arguments (which may contain zero or more values).
In these illustrations,
.Sq \&.Yo
opens the scope of a macro, and if specified,
.Sq \&.Yc
closes it out (closure may be implicit at end-of-line or end-of-file).
.\" PARAGRAPH
.Pp
Block full-explicit (may contain head, body, tail).
.Bd -literal -offset XXXX
\&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBhead...\(rB
\(lBbody...\(rB
\&.Yc \(lBtail...\(rB
.Ed
.\" PARAGRAPH
.Pp
Block full-implicit (may contain zero or more heads, body, no tail).
.Bd -literal -offset XXXX
\&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBhead... \(lBTa head...\(rB\(rB
\(lBbody...\(rB
\&.Yc
.Ed
.\" PARAGRAPH
.Pp
Block partial-explicit (may contain head, multi-line body, tail).
.Bd -literal -offset XXXX
\&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBhead...\(rB
\(lBbody...\(rB
\&.Yc \(lBtail...\(rB
\&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBhead...\(rB \
\(lBbody...\(rB \&Yc \(lBtail...\(rB
.Ed
.\" PARAGRAPH
.Pp
Block partial-implicit (no head, body, no tail). Note that the body
section may be followed by zero or more
.Sx Reserved Words .
These are in the block scope, but not in the body scope.
.Bd -literal -offset XXXX
\&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBbody...\(rB \(lBreserved...\(rB
.Ed
.\" PARAGRAPH
.Pp
In-lines have \(>=0 scoped arguments.
.Bd -literal -offset XXX
\&.Yy \(lB\-arg \(lBval...\(rB\(rB \(lBargs...\(rB
\&.Yy \(lB\-arg \(lBval...\(rB\(rB arg0 arg1 argN
.Ed
.\" SECTION
.Sh MACROS
This section contains a complete list of all
.Nm
macros, arranged by classification. A
.Qq callable
macro is invoked subsequent to the initial macro-line macro. A
.Qq parsable
macro may be followed by further (ostensibly callable) macros.
.\" SUB-SECTION
.Ss Block full-implicit
The head of these macros follows invocation; the body is the content of
subsequent lines prior to closure. None of these macros have tails;
some
.Po
.Sq \&.It \-bullet ,
.Sq \-hyphen ,
.Sq \-dash ,
.Sq \-enum ,
.Sq \-item
.Pc
don't have heads.
.Pp
.Bl -column -compact -offset XXXX "MacroX" "CallableX" "ParsableX" "Closing"
.It Em Macro Ta Em Callable Ta Em Parsable Ta Em Closing
.It \&.Sh Ta \&No Ta \&No Ta \&.Sh
.It \&.Ss Ta \&No Ta \&No Ta \&.Sh, \&.Ss
.It \&.It Ta \&No Ta Yes Ta \&.It, \&.El
.El
.\" SUB-SECTION
.Ss Block full-explicit
None of these macros are callable or parsed. The last column indicates
the explicit scope rules. All contains bodies, some may contain heads
.Pq So \&Bf Sc .
.Pp
.Bl -column -compact -offset XXXX "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 \&.Ed Ta \&No Ta \&No Ta opened by \&.Bd
.It \&.Bl Ta \&No Ta \&No Ta closed by \&.El
.It \&.El Ta \&No Ta \&No Ta opened by \&.Bl
.It \&.Bf Ta \&No Ta \&No Ta closed by \&.Ef
.It \&.Ef Ta \&No Ta \&No Ta opened by \&.Bf
.It \&.Bk Ta \&No Ta \&No Ta closed by \&.Ek
.It \&.Ek Ta \&No Ta \&No Ta opened by \&.Bk
.El
.\" SUB-SECTION
.Ss Block partial-implicit
All of these are callable and parsed for further macros. Their scopes
close at the invocation's end-of-line.
.Pp
.Bl -column "MacroX" "CallableX" "ParsableX" -compact -offset XXXX
.It Em Macro Ta Em Callable Ta Em Parsable
.It \&.Aq Ta Yes Ta Yes
.It \&.Op Ta Yes Ta Yes
.It \&.Bq Ta Yes Ta Yes
.It \&.Dq Ta Yes Ta Yes
.It \&.Pq Ta Yes Ta Yes
.It \&.Qq Ta Yes Ta Yes
.It \&.Sq Ta Yes Ta Yes
.It \&.Brq Ta Yes Ta Yes
.It \&.D1 Ta \&No Ta \&Yes
.It \&.Dl Ta \&No Ta Yes
.It \&.Ql Ta Yes Ta Yes
.El
.\" PARAGRAPH
.Pp
The
.Sq \&.Op
may be broken by
.Sq \&.Oc
as in the following example:
.Bd -literal -offset XXXX
\&.Oo
\&.Op Fl a Oc
.Ed
.Pp
In the above example, the scope of
.Sq \&.Op
is technically broken by
.Sq \&.Oc ,
however, due to the overwhelming existence of this sequence, it's
allowed.
.\" SUB-SECTION
.Ss Block partial-explicit
Each of these contains at least a body and, in limited circumstances, a
head
.Pq So \&.Fo Sc , So \&.Eo Sc
and/or tail
.Pq So \&.Ec Sc .
.Pp
.Bl -column "MacroX" "CallableX" "ParsableX" "closed by XXXX" -compact -offset XXXX
.It Em Macro Ta Em Callable Ta Em Parsable Ta Em Scope
.It \&.Ao Ta Yes Ta Yes Ta closed by \&.Ac
.It \&.Ac Ta Yes Ta Yes Ta opened by \&.Ao
.It \&.Bc Ta Yes Ta Yes Ta closed by \&.Bo
.It \&.Bo Ta Yes Ta Yes Ta opened by \&.Bc
.It \&.Pc Ta Yes Ta Yes Ta closed by \&.Po
.It \&.Po Ta Yes Ta Yes Ta opened by \&.Pc
.It \&.Do Ta Yes Ta Yes Ta closed by \&.Dc
.It \&.Dc Ta Yes Ta Yes Ta opened by \&.Do
.It \&.Xo Ta Yes Ta Yes Ta closed by \&.Xc
.It \&.Xc Ta Yes Ta Yes Ta opened by \&.Xo
.It \&.Bro Ta Yes Ta Yes Ta closed by \&.Brc
.It \&.Brc Ta Yes Ta Yes Ta opened by \&.Bro
.It \&.Oc Ta Yes Ta Yes Ta closed by \&.Oo
.It \&.Oo Ta Yes Ta Yes Ta opened by \&.Oc
.It \&.So Ta Yes Ta Yes Ta closed by \&.Sc
.It \&.Sc Ta Yes Ta Yes Ta opened by \&.So
.It \&.Fc Ta Yes Ta Yes Ta opened by \&.Fo
.It \&.Fo Ta \&No Ta \&No Ta closed by \&.Fc
.It \&.Ec Ta Yes Ta Yes Ta opened by \&.Eo
.It \&.Eo Ta Yes Ta Yes Ta closed by \&.Ec
.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
.El
.\" SUB-SECTION
.Ss In-line
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.
.Pp
.Bl -column "MacroX" "CallableX" "ParsableX" "Arguments" -compact -offset XXXX
.It Em Macro Ta Em Callable Ta Em Parsable Ta Em Arguments
.It \&.Dd Ta \&No Ta \&No Ta >0
.It \&.Dt Ta \&No Ta \&No Ta n
.It \&.Os Ta \&No Ta \&No Ta n
.It \&.Pp Ta \&No Ta \&No Ta 0
.It \&.Ad Ta Yes Ta Yes Ta n
.It \&.An Ta Yes Ta Yes Ta n
.It \&.Ar Ta Yes Ta Yes Ta n
.It \&.Cd Ta Yes Ta \&No Ta >0
.It \&.Cm Ta Yes Ta Yes Ta n
.It \&.Dv Ta Yes Ta Yes Ta n
.It \&.Er Ta Yes Ta Yes 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 \&.Ft Ta Yes Ta Yes Ta n
.It \&.Ic Ta Yes Ta Yes Ta >0
.It \&.In Ta \&No Ta \&No Ta n
.It \&.Li Ta Yes Ta Yes Ta n
.It \&.Nd Ta \&No Ta \&No Ta n
.It \&.Nm Ta Yes Ta Yes Ta n
.It \&.Ot Ta \&No Ta \&No Ta n
.It \&.Pa Ta Yes Ta Yes Ta n
.It \&.Rv Ta \&No Ta \&No Ta 0
.It \&.St Ta \&No Ta Yes Ta 1
.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 \&.%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 \&.At Ta Yes Ta Yes Ta 1
.It \&.Bsx Ta Yes Ta Yes Ta n
.It \&.Bx Ta Yes Ta Yes Ta n
.It \&.Db Ta \&No Ta \&No Ta 1
.It \&.Em Ta Yes Ta Yes Ta >0
.It \&.Fx Ta Yes Ta Yes Ta n
.It \&.Ms Ta Yes Ta Yes Ta >0
.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 \&.Ox Ta Yes Ta Yes Ta n
.It \&.Pf Ta \&No Ta Yes Ta 1
.It \&.Sm Ta \&No Ta \&No 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 \&.Ux Ta Yes Ta Yes Ta n
.It \&.Dx Ta Yes Ta Yes Ta n
.It \&.Bt Ta \&No Ta \&No Ta 0
.It \&.Hf Ta \&No Ta \&No Ta n
.It \&.Fr Ta \&No Ta \&No Ta n
.It \&.Ud Ta \&No Ta \&No Ta 0
.It \&.Lb Ta \&No Ta \&No Ta 1
.It \&.Ap Ta Yes Ta Yes Ta 0
.It \&.Lp Ta \&No Ta \&No Ta 0
.It \&.Lk Ta Yes Ta Yes Ta n
.It \&.Mt Ta Yes Ta Yes Ta >0
.It \&.Es Ta \&No Ta \&No Ta 0
.It \&.En Ta \&No Ta \&No Ta 0
.El
.Pp
The
.Sq \&.Ot ,
.Sq \&.Fr ,
.Sq \&.Es
and
.Sq \&.En ,
macros are obsolete.
.\" 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 .
.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.
.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.
.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
