===================================================================
RCS file: /cvs/mandoc/roff.7,v
retrieving revision 1.50
retrieving revision 1.62
diff -u -p -r1.50 -r1.62
--- mandoc/roff.7	2014/03/30 19:47:48	1.50
+++ mandoc/roff.7	2015/01/20 19:39:34	1.62
@@ -1,4 +1,4 @@
-.\"	$Id: roff.7,v 1.50 2014/03/30 19:47:48 schwarze Exp $
+.\"	$Id: roff.7,v 1.62 2015/01/20 19:39:34 schwarze Exp $
 .\"
 .\" Copyright (c) 2010, 2011, 2012 Kristaps Dzonsons <kristaps@bsd.lv>
 .\" Copyright (c) 2010, 2011, 2013, 2014 Ingo Schwarze <schwarze@openbsd.org>
@@ -15,7 +15,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: March 30 2014 $
+.Dd $Mdocdate: January 20 2015 $
 .Dt ROFF 7
 .Os
 .Sh NAME
@@ -239,8 +239,9 @@ pica (~1/6 inch)
 .It p
 point (~1/72 inch)
 .It f
-synonym for
+scale
 .Sq u
+by 65536
 .It v
 default vertical span
 .It m
@@ -254,7 +255,7 @@ width of rendered
 .Pq en
 character
 .It u
-default horizontal span
+default horizontal span for the terminal
 .It M
 mini-em (~1/100 em)
 .El
@@ -262,7 +263,6 @@ mini-em (~1/100 em)
 Using anything other than
 .Sq m ,
 .Sq n ,
-.Sq u ,
 or
 .Sq v
 is necessarily non-portable across output media.
@@ -402,31 +402,28 @@ language defines many more requests not implemented in
 .Ss \&ad
 Set line adjustment mode.
 This line-scoped request is intended to have one argument to select
-normal, left, right, or centre adjustment for subsequent text.
+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
 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.
+Since
+.Xr mandoc 1
+does not implement
+.Nm
+compatibility mode at all, it handles this request as an alias for
+.Sx \&am .
 .Ss \&as
 Append to a user-defined string.
 The syntax of this request is the same as that of
@@ -546,17 +543,23 @@ one explicit newline character.
 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.
+to a large, but finite number, and
+.Xr mandoc 1
+also limits the length of the expanded input line.
+Do not rely on the exact values of these limits.
 .Ss \&dei
 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.
+The request
+.Pp
+.D1 Pf . Cm \&dei Ar name Op Ar end
+.Pp
+has the same effect as:
+.Pp
+.D1 Pf . Cm \&de No \e* Ns Bo Ar name Bc Op \e* Ns Bq Ar end
 .Ss \&de1
 Define a
 .Nm
@@ -746,23 +749,19 @@ If the first character of COND is
 .Pq even page ,
 .Sq r
 .Pq register accessed ,
-or
 .Sq t
 .Pq troff mode ,
+or
+.Sq v
+.Pq vroff mode ,
 COND evaluates to false.
 .It
-If COND starts with a digit, optionally prefixed by a minus sign,
-it is evaluated as a numerical expression of the form
-.Ar number operator number ,
-where
-.Ar operator
-is one of
-.Sq < ,
-.Sq <= ,
-.Sq = ,
-.Sq >= ,
-or
-.Sq > .
+If COND starts with a parenthesis or with an optionally signed
+integer number, it is evaluated according to the rules of
+.Sx Numerical expressions
+explained below.
+It evaluates to true if the result is positive,
+or to false if the result is zero or negative.
 .It
 Otherwise, the first character of COND is regarded as a delimiter
 and COND evaluates to true if the string extending from its first
@@ -878,12 +877,14 @@ request are discarded.
 Change the output line length.
 Its syntax is as follows:
 .Pp
-.D1 Pf . Cm \&ll Op Ar width
+.D1 Pf . Cm \&ll Op Oo +|- Oc Ns Ar width
 .Pp
 If the
 .Ar width
 argument is omitted, the line length is reset to its previous value.
 The default setting for terminal output is 78n.
+If a sign is given, the line length is added to or subtracted from;
+otherwise, it is set to the provided value.
 Using this request in new manuals is discouraged for several reasons,
 among others because it overrides the
 .Xr mandoc 1
@@ -896,23 +897,19 @@ 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 or change 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 Oo +|- Oc Ns Ar value
+.D1 Pf \. Cm \&nr Ar name Oo +|- Oc Ns Ar expression
 .Pp
-The
-.Ar value
-may, at the moment, only be an integer.
+For the syntax of
+.Ar expression ,
+see
+.Sx Numerical expressions
+below.
 If it is prefixed by a sign, the register will be
 incremented or decremented instead of assigned to.
 .Pp
@@ -942,11 +939,26 @@ Turn on no-space mode.
 This line-scoped request is intended to take no arguments.
 Currently, it is ignored including its arguments,
 and the number of arguments is not checked.
+.Ss \&pl
+Change page length.
+This line-scoped request is intended to take one height argument.
+Currently, it is ignored including its arguments,
+and the number of arguments is not checked.
 .Ss \&ps
 Change point size.
 This line-scoped request is intended to take one numerical argument.
 Currently, it is ignored including its arguments,
 and the number of arguments is not checked.
+.Ss \&rm
+Remove a request, macro or string.
+Its syntax is as follows:
+.Pp
+.D1 Pf \. Cm \&rm Ar name
+.Ss \&rr
+Remove a register.
+Its syntax is as follows:
+.Pp
+.D1 Pf \. Cm \&rr Ar name
 .Ss \&so
 Include a source file.
 Its syntax is as follows:
@@ -1015,6 +1027,73 @@ Begin a table, which formats input in aligned rows and
 See
 .Xr tbl 7
 for a description of the tbl language.
+.Ss Numerical expressions
+The
+.Sx \&nr ,
+.Sx \&if ,
+and
+.Sx \&ie
+requests accept integer numerical expressions as arguments.
+These are always evaluated using the C
+.Vt int
+type; integer overflow works the same way as in the C language.
+Numbers consist of an arbitrary number of digits
+.Sq 0
+to
+.Sq 9
+prefixed by an optional sign
+.Sq +
+or
+.Sq - .
+.Pp
+The following binary operators are implemented.
+Unless otherwise stated, they behave as in the C language:
+.Pp
+.Bl -tag -width 2n -compact
+.It Ic +
+addition
+.It Ic -
+subtraction
+.It Ic *
+multiplication
+.It Ic /
+division
+.It Ic %
+remainder of division
+.It Ic <
+less than
+.It Ic >
+greater than
+.It Ic ==
+equal to
+.It Ic =
+equal to, same effect as
+.Ic ==
+(this differs from C)
+.It Ic <=
+less than or equal to
+.It Ic >=
+greater than or equal to
+.It Ic <>
+not equal to (corresponds to C
+.Ic != ;
+this one is of limited portability, it is supported by Heirloom roff,
+but not by groff)
+.It Ic &
+logical and (corresponds to C
+.Ic && )
+.It Ic \&:
+logical or (corresponds to C
+.Ic \&|| )
+.It Ic <?
+minimum (not available in C)
+.It Ic >?
+maximum (not available in C)
+.El
+.Pp
+There is no concept of precendence; evaluation proceeds from left to right,
+except when subexpressions are enclosed in parantheses.
+Inside parentheses, whitespace is ignored.
 .Sh ESCAPE SEQUENCE REFERENCE
 The
 .Xr mandoc 1
@@ -1103,10 +1182,15 @@ Digit width space character.
 Anchor definition; ignored by
 .Xr mandoc 1 .
 .Ss \eB\(aq Ns Ar string Ns \(aq
-Test whether
+Interpolate
+.Sq 1
+if
 .Ar string
-is a numerical expession; ignored by
-.Xr mandoc 1 .
+conforms to the syntax of
+.Sx Numerical expressions
+explained above and
+.Sq 0
+otherwise.
 .Ss \eb\(aq Ns Ar string Ns \(aq
 Bracket building function; ignored by
 .Xr mandoc 1 .
@@ -1114,8 +1198,10 @@ Bracket building function; ignored by
 .Sx Special Characters
 with names of arbitrary length.
 .Ss \ec
-Interrupt text processing to insert requests or macros; ignored by
-.Xr mandoc 1 .
+When encountered at the end of an input text line,
+the next input text line is considered to continue that line,
+even if there are request or macro lines in between.
+No whitespace is inserted.
 .Ss \eD\(aq Ns Ar string Ns \(aq
 Draw graphics function; ignored by
 .Xr mandoc 1 .
@@ -1230,9 +1316,13 @@ Vertical motion; ignored by
 .Xr mandoc 1 .
 .Ss \ew\(aq Ns Ar string Ns \(aq
 Interpolate the width of the
-.Ar string ;
-ignored by
-.Xr mandoc 1 .
+.Ar string .
+The
+.Xr mandoc 1
+implementation assumes that after expansion of user-defined strings, the
+.Ar string
+only contains normal characters, no escape sequences, and that each
+character has a width of 24 basic units.
 .Ss \eX\(aq Ns Ar string Ns \(aq
 Output
 .Ar string
@@ -1268,6 +1358,12 @@ The term
 refers to groff version 1.15.
 .Pp
 .Bl -dash -compact
+.It
+The
+.Sq u
+scaling unit is the default terminal unit.
+In traditional troff systems, this unit would change depending on the
+output media.
 .It
 In mandoc, the
 .Sx \&EQ ,