Document strftime %Ob and %OB as C2X features.

C2X standardizes strftime %Ob and %OB support.  This patch updates the
glibc manual to say these are C2X features, while noting that the
details of what is the alternative form of a month name are not
specified in C2X.

Note: C2X seems unclear to me about whether %h being equivalent to %b
means %Oh is thereby allowed and equivalent to %Ob; I've asked WG14.

Tested with "make info" and "make pdf".

	* manual/time.texi (strftime): Document %Ob and %OB as C2X
	features.

2 files changed, 16 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index 182aa13353..09c3d8f22e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2019-08-22  Joseph Myers  <joseph@codesourcery.com>
+
+	* manual/time.texi (strftime): Document %Ob and %OB as C2X
+	features.
+
 2019-08-21  Paul Eggert  <eggert@cs.ucla.edu>
 
 	Remove dead regex code
diff --git a/manual/time.texi b/manual/time.texi
index bfa46dd45b..c5f5b94b67 100644
--- a/manual/time.texi
+++ b/manual/time.texi
@@ -1352,7 +1352,11 @@ alternative numeric symbols.
 With @code{%B}, @code{%b}, and @code{%h}: use the grammatical form for
 month names that is appropriate when the month is named by itself,
 rather than the form that is appropriate when the month is used as
-part of a complete date.  This is a GNU extension.
+part of a complete date.  The @code{%OB} and @code{%Ob} formats are a
+C2X feature, specified in C2X to use the locale's `alternative' month
+name; @theglibc{} extends this specification to say that the form used
+in a complete date is the default and the form naming the month by
+itself is the alternative.
 @end table
 
 If the format supports the modifier but no alternative representation
@@ -1372,14 +1376,16 @@ The full weekday name according to the current locale.
 @item %b
 The abbreviated month name according to the current locale, in the
 grammatical form used when the month is part of a complete date.
-As a GNU extension, the @code{O} modifier can be used (@code{%Ob})
-to get the grammatical form used when the month is named by itself.
+As a C2X feature (with a more detailed specification in @theglibc{}),
+the @code{O} modifier can be used (@code{%Ob}) to get the grammatical
+form used when the month is named by itself.
 
 @item %B
 The full month name according to the current locale, in the
 grammatical form used when the month is part of a complete date.
-As a GNU extension, the @code{O} modifier can be used (@code{%OB})
-to get the grammatical form used when the month is named by itself.
+As a C2X feature (with a more detailed specification in @theglibc{}),
+the @code{O} modifier can be used (@code{%OB}) to get the grammatical
+form used when the month is named by itself.
 
 Note that not all languages need two different forms of the month
 names, so the text produced by @code{%B} and @code{%OB}, and by