.\" $Id$ .\" .\" Copyright (c) 2009 Kristaps Dzonsons .\" .\" 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 . . .Sh NAME .Nm mdoc .Nd mdoc language reference . . .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 . . .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 . . .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. . . .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. Macro lines with only a control charater and optionally whitespace are stripped from input. . . .Ss Reserved Characters Within a macro line, the following characters are reserved: .Pp .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 . .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. . . .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 . . . .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. . . .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 . . . .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 . .Pp In macro lines, whitespace delimits arguments and is discarded. If arguments are quoted, whitespace within the quotes is retained. . .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. . . .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. . .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 . .Pp In free-form mode, quotes are regarded as opaque text. . .Ss Dates TODO. . .Ss Scaling Widths Many macros support scaled widths for their arguments, such as stipulating a two-inch list indentation with the following: .Bd -literal -offset indent \&.Bl -tag -width 2i .Ed . .Pp The syntax for scaled widths is .Sq Li [+-]?[0-9]*.[0-9]*[:unit:] , where a decimal must be preceded or proceeded by at least one digit. Negative numbers, while accepted, are truncated to zero. The following scaling units are accepted: .Pp .Bl -tag -width Ds -offset indent -compact .It c centimetre .It i inch .It P pica (~1/6 inch) .It p point (~1/72 inch) .It f synonym for .Sq u .It v default vertical span .It m width of rendered .Sq m .Pq em character .It n width of rendered .Sq n .Pq en character .It u default horizontal span .It M mini-em (~1/100 em) .El .Pp Using anything other than .Sq m , .Sq n , .Sq u , or .Sq v is necessarily non-portable across output media. See .Sx COMPATIBILITY . . . .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 foo \&.Nd a description goes here \&.\e\*q The next is for sections 2 & 3 only. \&.\e\*q .Sh LIBRARY \&. \&.Sh SYNOPSIS \&.Nm foo \&.Op Fl options \&.Ar \&. \&.Sh DESCRIPTION The \&.Nm utility processes files ... \&.\e\*q .Sh IMPLEMENTATION NOTES \&.\e\*q The next is for sections 1 & 8 only. \&.\e\*q .Sh EXIT STATUS \&.\e\*q The next is for sections 2, 3, & 9 only. \&.\e\*q .Sh RETURN VALUES \&.\e\*q The next is for sections 1, 6, 7, & 8 only. \&.\e\*q .Sh ENVIRONMENT \&.\e\*q .Sh FILES \&.\e\*q .Sh EXAMPLES \&.\e\*q The next is for sections 1, 4, 6, 7, & 8 only. \&.\e\*q .Sh DIAGNOSTICS \&.\e\*q The next is for sections 2, 3, & 9 only. \&.\e\*q .Sh ERRORS \&.\e\*q .Sh SEE ALSO \&.\e\*q .Xr foobar 1 \&.\e\*q .Sh STANDARDS \&.\e\*q .Sh HISTORY \&.\e\*q .Sh AUTHORS \&.\e\*q .Sh CAVEATS \&.\e\*q .Sh BUGS \&.\e\*q .Sh SECURITY CONSIDERATIONS .Ed . .Pp Subsequent SYNOPSIS and DESCRIPTION sections are strongly encouraged, but non-compulsory. . . .Sh MACRO SYNTAX Macros are one to three three characters in length and begin with a control character , .Sq \&. , at the beginning of the line. An arbitrary amount of whitespace may sit between the control character and the macro name. Thus, .Sq \&.Pp and .Sq \&.\ \ \ \&Pp are equivalent. Macro names are two or three characters in length. . .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. . .Pp The .Em Callable column indicates that the macro may be called subsequent to the initial line-macro. If a macro is not callable, then its invocation after the initial line macro is interpreted as opaque text, such that .Sq \&.Fl \&Sh produces .Sq Fl \&Sh . . .Pp The .Em Parsable column indicates whether the macro may be followed by further (ostensibly callable) macros. If a macro is not parsable, subsequent macro invocations on the line will be interpreted as opaque text. . .Pp The .Em Scope column, if applicable, describes closure rules. . . .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 . .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 . . .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 . .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 . . .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 . .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 Sx \&Ao .It Sx \&Ao Ta Yes Ta Yes Ta closed by Sx \&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 Sx \&Re Ta \&No Ta \&No Ta opened by Sx \&Rs .It Sx \&Rs Ta \&No Ta \&No Ta closed by Sx \&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 . . .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 . .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 . . .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 . .Pp .Bl -column "MacroX" "CallableX" "ParsableX" "Arguments" -compact -offset indent .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Arguments .It Sx \&%A Ta \&No Ta \&No Ta >0 .It Sx \&%B Ta \&No Ta \&No Ta >0 .It Sx \&%C Ta \&No Ta \&No Ta >0 .It Sx \&%D Ta \&No Ta \&No Ta >0 .It Sx \&%I Ta \&No Ta \&No Ta >0 .It Sx \&%J Ta \&No Ta \&No Ta >0 .It Sx \&%N Ta \&No Ta \&No Ta >0 .It Sx \&%O Ta \&No Ta \&No Ta >0 .It Sx \&%P Ta \&No Ta \&No Ta >0 .It Sx \&%R Ta \&No Ta \&No Ta >0 .It Sx \&%T Ta \&No Ta \&No Ta >0 .It Sx \&%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 n .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 n .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 . . .Sh REFERENCE This section is a canonical reference of all macros, arranged alphabetically. For the scoping of individual macros, see .Sx MACRO SYNTAX . . .Ss \&%A Author name of an .Sx \&Rs block. Multiple authors should each be accorded their own .Sq \%%A line. .Pp Author names should be ordered with full or abbreviated forename(s) first, then full surname. .Ss \&%B Book title of an .Sx \&Rs block. This macro may also be used in a non-bibliographic context when referring to book titles. .Ss \&%C Publication city or location of an .Sx \&Rs block. .Pp .Em Compatibility remark : this macro is not implemented in .Xr groff 1 . .Ss \&%D Publication date of an .Sx \&Rs block. This should follow the canonical syntax for .Sx Dates . .Ss \&%I Publisher or issuer name of an .Sx \&Rs block. .Ss \&%J Journal name of an .Sx \&Rs block. .Ss \&%N Issue number (usually for journals) of an .Sx \&Rs block. .Ss \&%O Optional information of an .Sx \&Rs block. .Ss \&%P Book or journal page number of an .Sx \&Rs block. .Ss \&%Q Institutional author (school, government, etc.) of an .Sx \&Rs block. Multiple institutional authors should each be accorded their own .Sq \&%Q line. .Ss \&%R Technical report name of an .Sx \&Rs block. .Ss \&%T Article title of an .Sx \&Rs block. This macro may also be used in a non-bibliographical context when referring to article titles. .Ss \&%V Volume number of an .Sx \&Rs block. .Ss \&Ac Closes an .Sx \&Ao block. Does not have any tail arguments. .Ss \&Ad Address construct: usually in the context of an computational address in memory, not a physical (post) address. .Pp Example: .Bd -literal -offset indent \&.Ad [0,$] \&.Ad 0x00000000 .Ed .Ss \&An .Ss \&Ao Begins a block enclosed by angled brackets. Does not have any head arguments. .Pp Example: .Bd -literal -offset indent \&.Fl -key= Ns Ao Ar val Ac .Ed .Pp Note that, although this is overwhelmingly used to note URIs, the .Sx \&Lk and .Sx \&Mt macros are better suited for this purpose. .Ss \&Ap .Ss \&Aq .Ss \&Ar .Ss \&At .Ss \&Bc .Ss \&Bd .Ss \&Bf .Ss \&Bk .Ss \&Bl .Ss \&Bo .Ss \&Bq .Ss \&Brc .Ss \&Bro .Ss \&Brq .Ss \&Bsx .Ss \&Bt .Ss \&Bx .Ss \&Cd .Ss \&Cm .Ss \&D1 .Ss \&Db .Ss \&Dc .Ss \&Dd .Ss \&Dl .Ss \&Do .Ss \&Dq .Ss \&Dt .Ss \&Dv .Ss \&Dx .Ss \&Ec .Ss \&Ed .Ss \&Ef .Ss \&Ek .Ss \&El .Ss \&Em .Ss \&En .Ss \&Eo .Ss \&Er .Ss \&Es .Ss \&Ev .Ss \&Ex .Ss \&Fa .Ss \&Fc .Ss \&Fd .Ss \&Fl .Ss \&Fn .Ss \&Fo .Ss \&Fr .Ss \&Ft .Ss \&Fx .Ss \&Hf .Ss \&Ic .Ss \&In .Ss \&It .Ss \&Lb .Ss \&Li .Ss \&Lk .Ss \&Lp .Ss \&Ms .Ss \&Mt .Ss \&Nd .Ss \&Nm .Ss \&No .Ss \&Ns .Ss \&Nx .Ss \&Oc .Ss \&Oo .Ss \&Op .Ss \&Os .Ss \&Ot .Ss \&Ox .Ss \&Pa .Ss \&Pc .Ss \&Pf .Ss \&Po .Ss \&Pp .Ss \&Pq .Ss \&Qc .Ss \&Ql .Ss \&Qo .Ss \&Qq .Ss \&Re Closes a .Sx \&Rs block. Does not have any tail arguments. .Ss \&Rs Begins a bibliographic .Pq Dq reference block. Does not have any head arguments. The block macro and may only contain .Sx \&%A , .Sx \&%B , .Sx \&%C , .Sx \&%D , .Sx \&%I , .Sx \&%J , .Sx \&%N , .Sx \&%O , .Sx \&%P , .Sx \&%Q , .Sx \&%R , .Sx \&%T , and .Sx \&%V child macros (at least one must be specified). .Pp Example: .Bd -literal -offset indent \&.Rs \&.%A J. E. Hopcroft \&.%A J. D. Ullman \&.%B Introduction to Automata Theory, Languages, and Computation \&.%I Addison-Wesley \&.%C Reading, Massachusettes \&.%D 1979 \&.Re .Ed .Pp If an .Sx \&Rs block is used within a SEE ALSO section, a vertical space is asserted before the rendered output, else the block continues on the current line. .Ss \&Rv .Ss \&Sc .Ss \&Sh .Ss \&Sm .Ss \&So .Ss \&Sq .Ss \&Ss .Ss \&St .Ss \&Sx .Ss \&Sy .Ss \&Tn .Ss \&Ud .Ss \&Ux .Ss \&Va .Ss \&Vt .Ss \&Xc .Ss \&Xo .Ss \&Xr .Ss \&br .Ss \&sp . . .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 .It Negative scaling units are now truncated to zero instead of creating interesting conditions, such as with .Sq \&sp -1i . Furthermore, the .Sq f scaling unit, while accepted, is rendered as the default unit. .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. .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. .It The .Sq \&sp macro does not accept negative numbers. .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. .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. .It The vertical bar .Sq \(ba made historic groff .Qq go orbital but is a proper delimiter in this implementation. .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. .It .Sq \&It \-column syntax where column widths may be preceded by other arguments (instead of proceeded) is not supported. .It The .Sq \&At macro only accepts a single parameter. .It Some manuals use .Sq \&Li incorrectly by following it with a reserved character and expecting the delimiter to render. This is not supported. .It In groff, the .Sq \&Fo macro only produces the first parameter. This is no longer the case. .El . . .Sh SEE ALSO .Xr mandoc 1 , .Xr mandoc_char 7 . . .Sh AUTHORS The .Nm reference was written by .An Kristaps Dzonsons Aq kristaps@kth.se . . . .Sh CAVEATS There are many ambiguous parts of mdoc. . .Pp .Bl -dash -compact .It .Sq \&Fa should be .Sq \&Va as function arguments are variables. .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 . .It .Sq \&Va should formalise that only one or two arguments are acceptable: a variable name and optional, preceding type. .It .Sq \&Fd is ambiguous. It's commonly used to indicate an include file in the synopsis section. .Sq \&In should be used, instead. .It Only the .Sq \-literal argument to .Sq \&Bd makes sense. The remaining ones should be removed. .It The .Sq \&Xo and .Sq \&Xc macros should be deprecated. .It The .Sq \&Dt macro lacks clarity. It should be absolutely clear which title will render when formatting the manual page. .It A .Sq \&Lx should be provided for Linux (\(`a la .Sq \&Ox , .Sq \&Nx etc.). .It There's no way to refer to references in .Sq \&Rs/Re blocks. .It The \-split and \-nosplit dictates via .Sq \&An are re-set when entering and leaving the AUTHORS section. .El .