Tiny edit required after MDOC_HALT change.

[mandoc.git] / roff.7

diff --git a/roff.7 b/roff.7
index 4c582588532132a287f94878c78808e653b251e6..f34f191ab068465ddbdbf14ef3eebcbbb8c122a5 100644 (file)
--- a/roff.7
+++ b/roff.7
@@ -1,6 +1,7 @@
-.\"    $Id: roff.7,v 1.5 2010/05/17 02:38:13 kristaps Exp $
+.\"    $Id: roff.7,v 1.19 2010/12/29 15:21:34 kristaps Exp $

 .\"
 .\" Copyright (c) 2010 Kristaps Dzonsons <kristaps@bsd.lv>
 .\"
 .\" Copyright (c) 2010 Kristaps Dzonsons <kristaps@bsd.lv>

+.\" Copyright (c) 2010 Ingo Schwarze <schwarze@openbsd.org>

 .\"
 .\" Permission to use, copy, modify, and distribute this software for any
 .\" purpose with or without fee is hereby granted, provided that the above
 .\"
 .\" Permission to use, copy, modify, and distribute this software for any
 .\" purpose with or without fee is hereby granted, provided that the above


@@ -14,87 +15,296 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"

-.Dd $Mdocdate: May 17 2010 $
+.Dd $Mdocdate: December 29 2010 $

 .Dt ROFF 7
 .Os
 .Sh NAME
 .Nm roff
 .Dt ROFF 7
 .Os
 .Sh NAME
 .Nm roff

-.Nd roff language reference
+.Nd roff language reference for mandoc

 .Sh DESCRIPTION
 The
 .Nm roff
 .Sh DESCRIPTION
 The
 .Nm roff

-language is a general-purpose text-formatting language.  The purpose of
-this document is to consistently describe those language constructs
-accepted by the
+language is a general purpose text formatting language.
+In particular, it serves as the basis for the
+.Xr mdoc 7
+and
+.Xr man 7
+manual formatting macro languages.
+This manual describes the subset of the
+.Nm
+language accepted by the

 .Xr mandoc 1
 .Xr mandoc 1

-utility.  It is a work in progress.
+utility.

 .Pp
 .Pp

-An
-.Nm
-document follows simple rules:  lines beginning with the control
-characters
-.Sq \.
+Input lines beginning with the control characters
+.Sq \&.

 or
 .Sq \(aq
 or
 .Sq \(aq

-are parsed for macros.  Other lines are interpreted within the scope of
-prior macros:
-.Bd -literal -offset indent
-\&.xx Macro lines change control state.
-Other lines are interpreted within the current state.
-.Ed
+are parsed for requests and macros.
+These define the document structure, change the processing state
+and manipulate the formatting.
+Some requests and macros also produce formatted output,
+while others do not.
+.Pp
+All other input lines provide free-form text to be printed;
+the formatting of free-form text depends on the respective
+processing context.

 .Sh LANGUAGE SYNTAX
 .Nm
 documents may contain only graphable 7-bit ASCII characters, the space
 .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
+character, and, in certain circumstances, the tab character.
+To produce other characters in the output, use the escape sequences
+documented in the
+.Xr mandoc_char 7
+manual.
+.Pp
+All manuals must have

 .Ux
 line terminators.
 .Ux
 line terminators.

-.Sh MACRO SYNTAX
-Macros are arbitrary in length and begin with a control character ,
-.Sq \.
+.Sh REQUEST SYNTAX
+A request or macro line consists of:
+.Pp
+.Bl -enum -compact
+.It
+the control character
+.Sq \&.

 or
 or

-.Sq \(aq ,
-at the beginning of the line.
-An arbitrary amount of whitespace may sit between the control character
-and the macro name.
-Thus, the following are equivalent:
+.Sq \(aq
+at the beginning of the line,
+.It
+optionally an arbitrary amount of whitespace,
+.It
+the name of the request or the macro, which is one word of arbitrary
+length, terminated by whitespace,
+.It
+and zero or more arguments delimited by whitespace.
+.El
+.Pp
+Thus, the following request lines are all equivalent:

 .Bd -literal -offset indent
 .Bd -literal -offset indent

-\&.if
-\&.\ \ \ \&if
+\&.ig end
+\&.ig    end
+\&.   ig end

 .Ed
 .Ed

-.Sh REFERENCE
-This section is a canonical reference of all macros, arranged
-alphabetically.
+.Sh REQUEST REFERENCE
+The
+.Xr mandoc 1
+.Nm
+parser recognizes the following requests.
+Note that the
+.Nm
+language defines many more requests not implemented in
+.Xr mandoc 1 .
+.Ss \&ad
+Set line adjustment mode.
+This line-scoped request is intended to have one argument to select
+normal, left, right, or center adjustment for subsequent text.
+Currently, it is ignored including its arguments,
+and the number of arguments is not checked.

 .Ss \&am
 .Ss \&am

-The syntax of this macro is the same as that of
-.Sx \&ig ,
-except that a leading argument must be specified.
-It is ignored, as are its children.
+Append to a macro definition.
+The syntax of this request is the same as that of
+.Sx \&de .
+It is currently ignored by
+.Xr mandoc 1 ,
+as are its children.

 .Ss \&ami
 .Ss \&ami

-The syntax of this macro is the same as that of
-.Sx \&ig ,
-except that a leading argument must be specified.
-It is ignored, as are its children.
+Append to a macro definition, specifying the macro name indirectly.
+The syntax of this request is the same as that of
+.Sx \&dei .
+It is currently ignored by
+.Xr mandoc 1 ,
+as are its children.

 .Ss \&am1
 .Ss \&am1

-The syntax of this macro is the same as that of
-.Sx \&ig ,
-except that a leading argument must be specified.
-It is ignored, as are its children.
+Append to a macro definition, switching roff compatibility mode off
+during macro execution.
+The syntax of this request is the same as that of
+.Sx \&de1 .
+It is currently ignored by
+.Xr mandoc 1 ,
+as are its children.

 .Ss \&de
 .Ss \&de

-The syntax of this macro is the same as that of
-.Sx \&ig ,
-except that a leading argument must be specified.
-It is ignored, as are its children.
+Define a
+.Nm
+macro.
+Its syntax can be either
+.Bd -literal -offset indent
+.Pf . Cm \&de Ar name
+.Ar macro definition
+\&..
+.Ed
+.Pp
+or
+.Bd -literal -offset indent
+.Pf . Cm \&de Ar name Ar end
+.Ar macro definition
+.Pf . Ar end
+.Ed
+.Pp
+Both forms define or redefine the macro
+.Ar name
+to represent the
+.Ar macro definition ,
+which may consist of one or more input lines, including the newline
+characters terminating each line, optionally containing calls to
+.Nm
+requests,
+.Nm
+macros or high-level macros like
+.Xr man 7
+or
+.Xr mdoc 7
+macros, whichever applies to the document in question.
+.Pp
+Specifying a custom
+.Ar end
+macro works in the same way as for
+.Sx \&ig ;
+namely, the call to
+.Sq Pf . Ar end
+first ends the
+.Ar macro definition ,
+and after that, it is also evaluated as a
+.Nm
+request or
+.Nm
+macro, but not as a high-level macro.
+.Pp
+The macro can be invoked later using the syntax
+.Pp
+.D1 Pf . Ar name Op Ar argument Op Ar argument ...
+.Pp
+Arguments are separated by blank characters and can be quoted
+using double-quotes
+.Pq Sq \(dq
+to allow inclusion of blank characters into arguments.
+To include the double-quote character into a quoted argument,
+escape it from ending the argument by doubling it.
+.Pp
+The line invoking the macro will be replaced
+in the input stream by the
+.Ar macro definition ,
+replacing all occurrences of
+.No \e\e$ Ns Ar N ,
+where
+.Ar N
+is a digit, by the
+.Ar N Ns th Ar argument .
+For example,
+.Bd -literal -offset indent
+\&.de ZN
+\efI\e^\e\e$1\e^\efP\e\e$2
+\&..
+\&.ZN XtFree .
+.Ed
+.Pp
+produces
+.Pp
+.D1 \efI\e^XtFree\e^\efP.
+.Pp
+in the input stream, and thus in the output: \fI\^XtFree\^\fP.
+.Pp
+Since macros and user-defined strings share a common string table,
+defining a macro
+.Ar name
+clobbers the user-defined string
+.Ar name ,
+and the
+.Ar macro definition
+can also be printed using the
+.Sq \e*
+string interpolation syntax described below
+.Sx ds ,
+but this is rarely useful because every macro definition contains at least
+one explicit newline character.
+.Pp
+In order to prevent endless recursion, both groff and
+.Xr 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.

 .Ss \&dei
 .Ss \&dei

-The syntax of this macro is the same as that of
-.Sx \&ig ,
-except that a leading argument must be specified.
-It is ignored, as are its children.
+Define a
+.Nm
+macro, specifying the macro name indirectly.
+The syntax of this request is the same as that of
+.Sx \&de .
+It is currently ignored by
+.Xr mandoc 1 ,
+as are its children.

 .Ss \&de1
 .Ss \&de1

-The syntax of this macro is the same as that of
-.Sx \&ig ,
-except that a leading argument must be specified.
-It is ignored, as are its children.
+Define a
+.Nm
+macro that will be executed with
+.Nm
+compatibility mode switched off during macro execution.
+This is a GNU extension not available in traditional
+.Nm
+implementations and not even in older versions of groff.
+Since
+.Xr mandoc 1
+does not implement
+.Nm
+compatibility mode at all, it handles this request as an alias for
+.Sx \&de .
+.Ss \&ds
+Define a user-defined string.
+Its syntax is as follows:
+.Pp
+.D1 Pf . Cm \&ds Ar name Oo \(dq Oc Ns Ar string
+.Pp
+The
+.Ar name
+and
+.Ar string
+arguments are space-separated.
+If the
+.Ar 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
+.Ar string ,
+including whitespace and double-quote characters, even trailing ones.
+.Pp
+The
+.Ar string
+can be interpolated into subsequent text by using
+.No \e* Ns Bq Ar name
+for a
+.Ar name
+of arbitrary length, or \e*(NN or \e*N if the length of
+.Ar 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.
+.Pp
+Since user-defined strings and macros share a common string table,
+defining a string
+.Ar name
+clobbers the macro
+.Ar name ,
+and the
+.Ar 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
+.Ar string ,
+forming a new input line passed to the
+.Nm
+parser.
+For example,
+.Bd -literal -offset indent
+\&.ds badidea .S
+\&.badidea
+H SYNOPSIS
+.Ed
+.Pp
+invokes the
+.Cm SH
+macro when used in a
+.Xr man 7
+document.
+Such abuse is of course strongly discouraged.

 .Ss \&el
 The
 .Qq else
 .Ss \&el
 The
 .Qq else


@@ -106,9 +316,12 @@ If no stack entries are present (e.g., due to no prior
 .Sx \&ie
 calls)
 then false is assumed.
 .Sx \&ie
 calls)
 then false is assumed.

-The syntax of this macro is similar to
+The syntax of this request is similar to

 .Sx \&if
 except that the conditional is missing.
 .Sx \&if
 except that the conditional is missing.

+.Ss \&hy
+Set automatic hyphenation mode.
+This line-scoped request is currently ignored.

 .Ss \&ie
 The
 .Qq if
 .Ss \&ie
 The
 .Qq if


@@ -120,56 +333,70 @@ which may be separated by any intervening input (or not exist at all).
 Its syntax is equivalent to
 .Sx \&if .
 .Ss \&if
 Its syntax is equivalent to
 .Sx \&if .
 .Ss \&if

-Begins a conditional that always evaluates to false.
+Begins a conditional.
+Right now, the conditional evaluates to true
+if and only if it starts with the letter
+.Sy 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,
 .Pp
 If a conditional is false, its children are not processed, but are
 syntactically interpreted to preserve the integrity of the input
 document.
 Thus,
 .Pp

-.D1 \&.if t \e .ig
+.D1 \&.if t .ig

 .Pp
 will discard the
 .Sq \&.ig ,
 which may lead to interesting results, but
 .Pp
 .Pp
 will discard the
 .Sq \&.ig ,
 which may lead to interesting results, but
 .Pp

-.D1 \&.if t \e .if t \e{\e
+.D1 \&.if t .if t \e{\e

 .Pp
 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.
 .Pp
 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 macro has the following syntax:
-.Pp
-.Bd -literal -offset indent -compact
+This request has the following syntax:
+.Bd -literal -offset indent

 \&.if COND \e{\e
 BODY...
 \&.\e}
 .Ed
 \&.if COND \e{\e
 BODY...
 \&.\e}
 .Ed

-.Bd -literal -offset indent -compact
+.Bd -literal -offset indent

 \&.if COND \e{ BODY
 BODY... \e}
 .Ed
 \&.if COND \e{ BODY
 BODY... \e}
 .Ed

-.Bd -literal -offset indent -compact
+.Bd -literal -offset indent

 \&.if COND \e{ BODY
 BODY...
 \&.\e}
 .Ed
 \&.if COND \e{ BODY
 BODY...
 \&.\e}
 .Ed

-.Bd -literal -offset indent -compact
+.Bd -literal -offset indent

 \&.if COND \e
 BODY
 .Ed
 .Pp
 \&.if COND \e
 BODY
 .Ed
 .Pp

-COND is a conditional (for the time being, this always evaluates to
-false).
+COND is a conditional statement.
+roff allows for complicated conditionals; mandoc is much simpler.
+At this time, mandoc supports only
+.Sq n ,
+evaluating to true;
+and
+.Sq t ,
+.Sq e ,
+and
+.Sq o ,
+evaluating to false.
+All other invocations are read up to the next end of line or space and
+evaluate as false.

 .Pp
 If the BODY section is begun by an escaped brace
 .Sq \e{ ,
 .Pp
 If the BODY section is begun by an escaped brace
 .Sq \e{ ,

-scope continues until a closing-brace macro
+scope continues until a closing-brace escape sequence

 .Sq \.\e} .
 .Sq \.\e} .

-If the BODY is not enclosed in braces, scope continues until the next
-macro or word.
+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
 If the COND is followed by a BODY on the same line, whether after a

-brace or not, then macros
+brace or not, then requests and macros

 .Em must
 begin with a control character.
 It is generally more intuitive, in this case, to write
 .Em must
 begin with a control character.
 It is generally more intuitive, in this case, to write


@@ -180,86 +407,330 @@ bar
 \&.\e}
 .Ed
 .Pp
 \&.\e}
 .Ed
 .Pp

-than having the macro follow as
+than having the request or macro follow as

 .Pp
 .D1 \&.if COND \e{ .foo
 .Pp
 The scope of a conditional is always parsed, but only executed if the
 conditional evaluates to true.
 .Pp
 .Pp
 .D1 \&.if COND \e{ .foo
 .Pp
 The scope of a conditional is always parsed, but only executed if the
 conditional evaluates to true.
 .Pp

-Note that text subsequent a
+Note that text following an

 .Sq \&.\e}
 .Sq \&.\e}

-macro is discarded.
+escape sequence is discarded.

 Furthermore, if an explicit closing sequence
 .Sq \e}
 is specified in a free-form line, the entire line is accepted within the
 Furthermore, if an explicit closing sequence
 .Sq \e}
 is specified in a free-form line, the entire line is accepted within the

-scope of the prior macro, not only the text preceding the close.
+scope of the prior request, not only the text preceding the close, with the
+.Sq \e}
+collapsing into a zero-width space.

 .Ss \&ig
 Ignore input.
 .Ss \&ig
 Ignore input.

-Accepts the following syntax:
-.Pp
-.Bd -literal -offset indent -compact
-\&.ig
-BODY...
+Its syntax can be either
+.Bd -literal -offset indent
+.Pf . Cm \&ig
+.Ar ignored text

 \&..
 .Ed
 \&..
 .Ed

-.Bd -literal -offset indent -compact
-\&.ig END
-BODY...
-\&.END
+.Pp
+or
+.Bd -literal -offset indent
+.Pf . Cm \&ig Ar end
+.Ar ignored text
+.Pf . Ar end

 .Ed
 .Pp
 In the first case, input is ignored until a
 .Sq \&..
 .Ed
 .Pp
 In the first case, input is ignored until a
 .Sq \&..

-macro is encountered on its own line.
-In the second case, input is ignored until a
-.Sq \&.END
-is encountered.
-Text subsequent the
-.Sq \&.END
-or
-.Sq \&..
-is discarded.
-.Pp
-Do not use the escape
+request is encountered on its own line.
+In the second case, input is ignored until the specified
+.Sq Pf . Ar end
+macro is encountered.
+Do not use the escape character

 .Sq \e
 .Sq \e

-anywhere in the definition of END.
-It causes very strange behaviour.
-Furthermore, if you redefine a
-.Nm
-macro, such as
+anywhere in the definition of
+.Ar end ;
+it would cause very strange behaviour.
+.Pp
+When the
+.Ar end
+macro is a roff request or a roff macro, like in

 .Pp
 .D1 \&.ig if
 .Pp
 the subsequent invocation of
 .Sx \&if
 .Pp
 .D1 \&.ig if
 .Pp
 the subsequent invocation of
 .Sx \&if

-will first signify the end of comment, then be invoked as a macro.
-This behaviour really shouldn't be counted upon.
+will first terminate the
+.Ar ignored text ,
+then be invoked as usual.
+Otherwise, it only terminates the
+.Ar ignored text ,
+and arguments following it or the
+.Sq \&..
+request are discarded.
+.Ss \&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.
+.Ss \&nh
+Turn off automatic hyphenation mode.
+This line-scoped request is currently ignored.
+.Ss \&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.
+.Ss \&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:
+.Pp
+.D1 Pf \. Cm \&nr Ar name Ar value
+.Pp
+The
+.Ar value
+may, at the moment, only be an integer.
+So far, only the following register
+.Ar name
+is recognised:
+.Bl -tag -width Ds
+.It Cm nS
+If set to a positive integer value, certain
+.Xr mdoc 7
+macros will behave in the same way as in the
+.Em SYNOPSIS
+section.
+If set to 0, these macros will behave in the same way as outside the
+.Em SYNOPSIS
+section, even when called within the
+.Em SYNOPSIS
+section itself.
+Note that starting a new
+.Xr mdoc 7
+section with the
+.Cm \&Sh
+macro will reset this register.
+.El
+.Ss \&so
+Include a source file.
+Its syntax is as follows:
+.Pp
+.D1 Pf \. Cm \&so Ar file
+.Pp
+The
+.Ar file
+will be read and its contents processed as input in place of the
+.Sq \&.so
+request line.
+To avoid inadvertant inclusion of unrelated files,
+.Xr mandoc 1
+only accepts relative paths not containing the strings
+.Qq ../
+and
+.Qq /.. .
+.Ss \&tr
+Output character translation.
+This request is intended to have one argument,
+consisting of an even number of characters.
+Currently, it is ignored including its arguments,
+and the number of arguments is not checked.
+.\" .Ss \&T&
+.\" Re-start a table layout, retaining the options of the prior table
+.\" invocation.
+.\" See
+.\" .Sx \&TS .
+.\" .Ss \&TE
+.\" End a table context.
+.\" See
+.\" .Sx \&TS .
+.\" .Ss \&TS
+.\" Begin a table, which formats input in aligned rows and columns.
+.\" A table consists of an optional single line of table options terminated
+.\" by a semicolon, followed by one or more lines of layout specification
+.\" terminated by a period, then table data.
+.\" A table block may also include
+.\" .Nm ,
+.\" .Xr mdoc 7 ,
+.\" or
+.\" .Xr man 7
+.\" macros.
+.\" .Pp
+.\" Table data is
+.\" .Em pre-processed ,
+.\" that is, data rows are parsed then inserted into the underlying stream
+.\" of input data.
+.\" This allows data rows to be interspersed by arbitrary macros, such as
+.\" .Bd -literal -offset indent
+.\" \&.TS
+.\" c c c.
+.\" 1 2 3
+.\" \&.Ao
+.\" 3 2 1
+.\" \&.Ac
+.\" \&.TE
+.\" .Ed
+.\" .Pp
+.\" in the case of
+.\" .Xr mdoc 7
+.\" or
+.\" .Bd -literal -offset indent
+.\" \&.TS
+.\" c c c.
+.\" \&.ds ab 2
+.\" 1 \e*(ab 3
+.\" \&.I
+.\" 3 2 1
+.\" \&.TE
+.\" .Ed
+.\" .Pp
+.\" in the case of
+.\" .Xr man 7 .
+.\" .Pp
+.\" The first line of a table consists of its options, which consists of
+.\" space-separated keys and modifiers terminated by a semicolon.
+.\" If the first line does not have a terminating semicolon, it is assumed
+.\" that no options are specified and instead a layout is processed.
+.\" Some options accept arguments enclosed by paranthesis.
+.\" The following case-insensitive options are available:
+.\" .Bl -tag -width Ds
+.\" .It Cm center
+.\" This may also be invoked with
+.\" .Cm centre .
+.\" .It Cm delim
+.\" Accepts a two-character argument.
+.\" This option is ignored.
+.\" .It Cm expand
+.\" .It Cm box
+.\" This may also be invoked with
+.\" .Cm frame .
+.\" .It Cm doublebox
+.\" This may also be invoked with
+.\" .Cm doubleframe .
+.\" .It Cm allbox
+.\" .It Cm tab
+.\" Accepts a single character argument used as the delimiter for cells in
+.\" data rows.
+.\" .It Cm linesize
+.\" Accepts a natural number (all digits) used as the line width for drawing
+.\" boxes.
+.\" .It Cm nokeep
+.\" .It Cm decimalpoint
+.\" .It Cm nospaces
+.\" .El
+.\" .Pp
+.\" The table layout follows table options, except in the case of
+.\" .Sx \&T& ,
+.\" where it immediately procedes invocation.
+.\" Layout specifies how data rows are displayed on output.
+.\" Each layout line corresponds to a line of data; the last layout line
+.\" applies to all remaining data lines.
+.\" Layout lines may also be separated by a comma.
+.\" Each layout cell consists of one of the following case-insensitive keys:
+.\" .Bl -tag -width Ds
+.\" .It Cm c
+.\" .It Cm r
+.\" .It Cm l
+.\" .It Cm n
+.\" .It Cm s
+.\" .It Cm a
+.\" .It Cm ^
+.\" .It Cm \-
+.\" This may also be invoked with
+.\" .Cm _ .
+.\" .It Cm =
+.\" .It Cm \(ba
+.\" .It Cm \(ba\(ba
+.\" .El
+.\" Keys may be followed by a set of modifiers.
+.\" A modifier is either a modifier key or a natural number for specifying
+.\" spacing.
+.\" The following case-insensitive modifier keys are available:
+.\" .Bl -tag -width Ds
+.\" .It Cm z
+.\" .It Cm u
+.\" .It Cm e
+.\" .It Cm t
+.\" .It Cm d
+.\" .It Cm f
+.\" Must be followed by a case-insensitive font style:
+.\" .Cm b
+.\" for bold or
+.\" .Cm i
+.\" for italic.
+.\" .It Cm b
+.\" .It Cm i
+.\" .El

 .Sh COMPATIBILITY
 This section documents compatibility between mandoc and other other
 .Sh COMPATIBILITY
 This section documents compatibility between mandoc and other other

-troff implementations, at this time limited to GNU troff
+.Nm
+implementations, at this time limited to GNU troff

 .Pq Qq groff .
 The term
 .Qq historic groff
 .Pq Qq groff .
 The term
 .Qq historic groff

-refers to groff versions before the
-.Pa doc.tmac
-file re-write
-.Pq somewhere between 1.15 and 1.19 .
+refers to groff version 1.15.

 .Pp
 .Bl -dash -compact
 .It
 .Pp
 .Bl -dash -compact
 .It

-Historic groff did not accept white-space buffering the custom END tag
-for the
+The
+.Cm nS
+register is only compatible with OpenBSD's groff-1.15.
+.It
+Historic groff did not accept white-space before a custom
+.Ar end
+macro for the

 .Sx \&ig
 .Sx \&ig

-macro.
+request.

 .It
 The
 .Sx \&if
 and family would print funny white-spaces with historic groff when
 .It
 The
 .Sx \&if
 and family would print funny white-spaces with historic groff when

-depending on next-line syntax.
+using the next-line syntax.

 .El
 .El

+.Sh SEE ALSO
+.Xr mandoc 1 ,
+.Xr man 7 ,
+.Xr mandoc_char 7 ,
+.Xr mdoc 7
+.\" .Rs
+.\" .%A M. E. Lesk
+.\" .%T Tbl\(emA Program to Format Tables
+.\" .%D June 11, 1976
+.\" .%U http://www.kohala.com/start/troff/v7/man/tbl/tbl.ps
+.\" .Re
+.Rs
+.%A Joseph F. Ossanna
+.%A Brian W. Kernighan
+.%I AT&T Bell Laboratories
+.%T Troff User's Manual
+.%R Computing Science Technical Report
+.%N 54
+.%C Murray Hill, New Jersey
+.%D 1976 and 1992
+.%U http://www.kohala.com/start/troff/cstr54.ps
+.Re
+.Rs
+.%A Joseph F. Ossanna
+.%A Brian W. Kernighan
+.%A Gunnar Ritter
+.%T Heirloom Documentation Tools Nroff/Troff User's Manual
+.%D September 17, 2007
+.%U http://heirloom.sourceforge.net/doctools/troff.pdf
+.Re
+.Sh HISTORY
+The RUNOFF typesetting system was written in PL/1 for the CTSS
+operating system by Jerome ("Jerry") E. Saltzer in 1961.
+It was first used as the main documentation tool by Multics since 1963.
+Robert ("Bob") H. Morris ported it to the GE-635 and called it
+.Nm ,
+Doug McIlroy rewrote it in BCPL in 1969,
+Joseph F. Ossanna rewrote it in PDP-11 assembly in 1973,
+and Brian W. Kernighan rewrote it in C in 1975.

 .Sh AUTHORS
 .Sh AUTHORS

-The
+.An -nosplit
+This partial

 .Nm
 reference was written by
 .Nm
 reference was written by

-.An Kristaps Dzonsons Aq kristaps@bsd.lv .
+.An Kristaps Dzonsons Aq kristaps@bsd.lv
+and
+.An Ingo Schwarze Aq schwarze@openbsd.org .