Move our partial roff language manual to the right place,

such that, after some more improvements, we will eventually
be able to install it.
jmc@ agrees with the plan.

1 files changed, 532 insertions, 0 deletions

diff --git a/share/man/man7/roff.7 b/share/man/man7/roff.7
new file mode 100644
index 00000000000..b3492b97b16
--- /dev/null
+++ b/share/man/man7/roff.7
@@ -0,0 +1,532 @@
+.\"	$Id: roff.7,v 1.1 2010/11/27 21:57:23 schwarze Exp $
+.\"
+.\" 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
+.\" 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: November 27 2010 $
+.Dt ROFF 7
+.Os
+.Sh NAME
+.Nm roff
+.Nd roff language reference
+.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
+.Xr mandoc 1
+utility.  It is a work in progress.
+.Pp
+An
+.Nm
+document follows simple rules:  lines beginning with the control
+characters
+.Sq \.
+or
+.Sq \(aq
+are parsed for requests and 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
+.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.
+.Sh MACRO SYNTAX
+Requests and macros are arbitrary in length and begin with a control
+character,
+.Sq \.
+or
+.Sq \(aq ,
+at the beginning of the line.
+An arbitrary amount of whitespace may sit between the control character
+and the request or macro name.
+Thus, the following are equivalent:
+.Bd -literal -offset indent
+\&.if
+\&.\ \ \ \&if
+.Ed
+.Sh REQUEST REFERENCE
+This section is a canonical reference of all requests recognized by the
+.Xr mandoc 1
+.Nm
+parser.
+The
+.Nm
+language defines many more requests and macros not implemented in
+.Xr mandoc 1 .
+.Ss \&am
+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
+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
+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
+Define a user-defined
+.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
+A user-defined 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 user-defined 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 user-defined macros and 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.
+.Ss \&dei
+Define a user-defined
+.Nm
+macro, specifying the macro name indirectly.
+The syntax of this macro is the same as that of
+.Sx \&de .
+It is currently ignored by
+.Xr mandoc 1 ,
+as are its children.
+.Ss \&de1
+Define a user-defined
+.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 macro 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.
+.Pp
+Since user-defined strings and macros share a common string table,
+defining a string
+.Ar name
+clobbers the user-defined 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
+half of an if/else conditional.
+Pops a result off the stack of conditional evaluations pushed by
+.Sx \&ie
+and uses it as its conditional.
+If no stack entries are present (e.g., due to no prior
+.Sx \&ie
+calls)
+then false is assumed.
+The syntax of this macro is similar to
+.Sx \&if
+except that the conditional is missing.
+.Ss \&ie
+The
+.Qq if
+half of an if/else conditional.
+The result of the conditional is pushed into a stack used by subsequent
+invocations of
+.Sx \&el ,
+which may be separated by any intervening input (or not exist at all).
+Its syntax is equivalent to
+.Sx \&if .
+.Ss \&if
+Begins a conditional.
+Right now, the conditional evaluates to true
+if and only if it starts with the letter
+.Sy n ,
+indicating processing in
+.Xr nroff 1
+style as opposed to
+.Xr troff 1
+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
+.D1 \&.if t \e .ig
+.Pp
+will discard the
+.Sq \&.ig ,
+which may lead to interesting results, but
+.Pp
+.D1 \&.if t \e .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.
+This macro has the following syntax:
+.Pp
+.Bd -literal -offset indent -compact
+\&.if COND \e{\e
+BODY...
+\&.\e}
+.Ed
+.Bd -literal -offset indent -compact
+\&.if COND \e{ BODY
+BODY... \e}
+.Ed
+.Bd -literal -offset indent -compact
+\&.if COND \e{ BODY
+BODY...
+\&.\e}
+.Ed
+.Bd -literal -offset indent -compact
+\&.if COND \e
+BODY
+.Ed
+.Pp
+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{ ,
+scope continues until a closing-brace macro
+.Sq \.\e} .
+If the BODY is not enclosed in braces, scope continues until the next
+macro or word.
+If the COND is followed by a BODY on the same line, whether after a
+brace or not, then macros
+.Em must
+begin with a control character.
+It is generally more intuitive, in this case, to write
+.Bd -literal -offset indent
+\&.if COND \e{\e
+\&.foo
+bar
+\&.\e}
+.Ed
+.Pp
+than having the 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
+Note that text subsequent a
+.Sq \&.\e}
+macro is discarded.
+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, with the
+.Sq \e}
+collapsing into a zero-width space.
+.Ss \&ig
+Ignore input.
+Its syntax can be either
+.Bd -literal -offset indent
+.Pf . Cm \&ig
+.Ar ignored text
+\&..
+.Ed
+.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 \&..
+macro 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
+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
+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 \&..
+macro are discarded.
+.Ss \&rm
+Remove a request, macro or string.
+This macro 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.
+The
+.Ar name
+is defined up to the next whitespace.
+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 as if they were defined in the
+.Em SYNOPSIS
+section.
+Otherwise, this behaviour is unset (even if called within the
+.Em SYNOPSIS
+section itself).
+Note that invoking a new
+.Xr mdoc 7
+section will unset this value.
+.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 macro 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.
+.Sh COMPATIBILITY
+This section documents compatibility between mandoc and other other
+troff implementations, at this time limited to GNU troff
+.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 .
+.Pp
+.Bl -dash -compact
+.It
+The
+.Cm nS
+request to
+.Sx \&nr
+is only compatible with OpenBSD's groff.
+.It
+Historic groff did not accept white-space buffering the custom END tag
+for the
+.Sx \&ig
+macro.
+.It
+The
+.Sx \&if
+and family would print funny white-spaces with historic groff when
+depending on next-line syntax.
+.El
+.Sh AUTHORS
+.An -nosplit
+This partial
+.Nm
+reference was written by
+.An Kristaps Dzonsons Aq kristaps@bsd.lv
+and
+.An Ingo Schwarze Aq schwarze@openbsd.org .