===================================================================
RCS file: /cvs/mandoc/mdoc.7,v
retrieving revision 1.60
retrieving revision 1.61
diff -u -p -r1.60 -r1.61
--- mandoc/mdoc.7	2009/09/28 22:09:08	1.60
+++ mandoc/mdoc.7	2009/10/18 13:58:48	1.61
@@ -1,4 +1,4 @@
-.\"	$Id: mdoc.7,v 1.60 2009/09/28 22:09:08 kristaps Exp $
+.\"	$Id: mdoc.7,v 1.61 2009/10/18 13:58:48 kristaps Exp $
 .\"
 .\" Copyright (c) 2009 Kristaps Dzonsons <kristaps@kth.se>
 .\"
@@ -14,7 +14,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: September 28 2009 $
+.Dd $Mdocdate: October 18 2009 $
 .Dt MDOC 7
 .Os
 .
@@ -73,6 +73,7 @@ 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
@@ -208,7 +209,60 @@ considered literal text.  Thus, the following produces
 .Pp
 In free-form mode, quotes are regarded as opaque text.
 .
+.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
@@ -544,6 +598,13 @@ file re-write
 .
 .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