[groff] 13/17: groff_diff(7): Present "new" font family feature.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit 61274deb1816b57df5e63e110fc21535e5a8c467
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Wed Jun 7 12:50:15 2023 -0500

    groff_diff(7): Present "new" font family feature.
    
    * Introduce terminology of "abstract style" and "resolved font name".
    * Observe that the "sizes" directive in a device description file can
      also cause the requested type size to not match the selected one.
      ("sizes" limits the range and "sizescale" the precision of type
      sizes.)
---
 doc/groff.texi       |  6 +++---
 man/groff_diff.7.man | 44 +++++++++++++++++++++++++++++++++++++-------
 2 files changed, 40 insertions(+), 10 deletions(-)

diff --git a/doc/groff.texi b/doc/groff.texi
index be4c4fbcd..fb8e7bea4 100644
--- a/doc/groff.texi
+++ b/doc/groff.texi
@@ -11977,9 +11977,9 @@ the read-only string-valued register @code{.sr}.  Both 
are associated
 with the environment (@pxref{Environments}).
 
 For example, if a type size of 10.95 points is requested, and the
-nearest size permitted by a @code{sizes} request (or a @code{sizescale}
-directive in the device's @file{DESC} file) is 11 points, the latter
-value is used by the output driver.
+nearest size permitted by a @code{sizes} request (or by the @code{sizes}
+or @code{sizescale} directives in the device's @file{DESC} file) is 11
+points, the output driver uses the latter value.
 @endDefreg
 
 The @code{\s} escape sequence offers the following syntax forms that
diff --git a/man/groff_diff.7.man b/man/groff_diff.7.man
index e17bae1ee..e2aac847a 100644
--- a/man/groff_diff.7.man
+++ b/man/groff_diff.7.man
@@ -128,6 +128,33 @@ within can be of arbitrary length.
 .
 .
 .\" ====================================================================
+.SS "Fonts"
+.\" ====================================================================
+.
+GNU
+.I troff \" GNU
+groups typefaces into
+.I families
+containing each of the styles
+.RB \[lq] R \[rq],
+.RB \[lq] I \[rq],
+.RB \[lq] B \[rq],
+and
+.RB \[lq] BI \[rq].
+.
+So that a document need not be strongly coupled to a specific font
+family,
+in GNU
+.I troff \" GNU
+an output device can associate a style in the abstract sense with a
+mounting position.
+.
+Thus the default family can be combined with a style dynamically,
+producing a
+.I "resolved font name."
+.
+.
+.\" ====================================================================
 .SS Colors
 .\" ====================================================================
 .
@@ -298,6 +325,8 @@ and
 scaling units.
 .
 .
+.br
+.ne 2v
 .P
 Output devices may be limited in the type sizes they can employ.
 .
@@ -323,13 +352,15 @@ if a type size of 10.95\~points is requested,
 and the nearest size permitted by a
 .B sizes
 request
-(or a
+(or by the
+.B sizes
+or
 .B sizescale
-directive in the device's
+directives in the device's
 .I DESC
 file)
 is 11\~points,
-the latter value is used by the output driver.
+the output driver uses the latter value.
 .\" END Keep (roughly) parallel with groff.texi node "Using Fractional
 .\" Type Sizes".
 .
@@ -453,7 +484,7 @@ were opened with the
 request
 (that is,
 font translation and
-styles are applied),
+abstract styles are applied),
 without actually mounting it.
 .
 This test doesn't load the complete font,
@@ -674,13 +705,12 @@ Select font
 .IR xxx ,
 which may be a font name,
 mounting position,
-or registered style that is then combined with the current font family
-to select the typeface.
+or abstract style to select the typeface.
 .
 .B \[rs]f[]
 is a synonym of
 .BR \[rs]fP ;
-i.e.,
+that is,
 it selects the previous font.
 .
 .