Improve documentation of string-collate-* functions

* doc/lispref/strings.texi (Text Comparison): Improve wording and
indexing of 'string-collate-equalp' and 'string-collate-lessp'.

* etc/NEWS: Move the entry of 'string-collate-equalp' and
'string-collate-lessp' to "Lisp Changes" section and mark it as
documented.

2 files changed, 28 insertions, 22 deletions

diff --git a/doc/lispref/strings.texi b/doc/lispref/strings.texi
index f8685d9312c..8aa4539bd78 100644
--- a/doc/lispref/strings.texi
+++ b/doc/lispref/strings.texi
@@ -465,6 +465,7 @@ Representations}.
 @code{string-equal} is another name for @code{string=}.
 @end defun
 
+@cindex locale-dependent string equivalence
 @defun string-collate-equalp string1 string2 &optional locale ignore-case
 This function returns @code{t} if @var{string1} and @var{string2} are
 equal with respect to collation rules.  A collation rule is not only
@@ -493,6 +494,7 @@ systems.
 If @var{ignore-case} is non-@code{nil}, characters are converted to lower-case
 before comparing them.
 
+@vindex w32-collate-ignore-punctuation
 To emulate Unicode-compliant collation on MS-Windows systems,
 bind @code{w32-collate-ignore-punctuation} to a non-@code{nil} value, since
 the codeset part of the locale cannot be @code{"UTF-8"} on MS-Windows.
@@ -518,7 +520,7 @@ optional argument @var{ignore-case} is non-@code{nil}, the comparison
 ignores case differences.
 @end defun
 
-@cindex lexical comparison
+@cindex lexical comparison of strings
 @defun string< string1 string2
 @c (findex string< causes problems for permuted index!!)
 This function compares two strings a character at a time.  It
@@ -576,6 +578,7 @@ are used.
 @code{string-lessp} is another name for @code{string<}.
 @end defun
 
+@cindex locale-dependent string comparison
 @defun string-collate-lessp string1 string2 &optional locale ignore-case
 This function returns @code{t} if @var{string1} is less than
 @var{string2} in collation order.  A collation order is not only
@@ -594,15 +597,15 @@ for sorting (@pxref{Sequence Functions}):
 @end group
 @end example
 
-This behavior is system-dependent; punctuation and whitespace are
-never ignored on Cygwin, regardless of locale.
+This behavior is system-dependent; e.g., punctuation and whitespace
+are never ignored on Cygwin, regardless of locale.
 
 The optional argument @var{locale}, a string, overrides the setting of
 your current locale identifier for collation.  The value is system
 dependent; a @var{locale} @code{"en_US.UTF-8"} is applicable on POSIX
 systems, while it would be, e.g., @code{"enu_USA.1252"} on MS-Windows
-systems.  The @var{locale} @code{"POSIX"} lets @code{string-collate-lessp}
-behave like @code{string-lessp}:
+systems.  The @var{locale} value of @code{"POSIX"} or @code{"C"} lets
+@code{string-collate-lessp} behave like @code{string-lessp}:
 
 @example
 @group
diff --git a/etc/NEWS b/etc/NEWS
index dc3758f8eb2..180e48ffc36 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -181,23 +181,6 @@ for use in Emacs bug reports.
 hiding character but the default `.' can be used by let-binding the
 variable `read-hide-char'.
 
-** The new functions `string-collate-lessp' and `string-collate-equalp'
-preserve the collation order as defined by the system's locale(1)
-environment.  For the time being this is implemented for modern POSIX
-systems and for MS-Windows, for other systems they fall back to their
-counterparts `string-lessp' and `string-equal'.
-
-*** The ls-lisp package uses `string-collate-lessp' to sort file names.
-If you want the old, locale-independent sorting, customize the new
-option `ls-lisp-use-string-collate' to a nil value.
-
-*** The MS-Windows specific variable `w32-collate-ignore-punctuation',
-if set to a non-nil value, causes the above 2 functions to ignore
-symbol and punctuation characters when collating strings.  This
-emulates the behavior of modern Posix platforms when the locale's
-codeset is "UTF-8" (as in "en_US.UTF-8").  This is needed because
-MS-Windows doesn't support UTF-8 as codeset in its locales.
-
 +++
 ** The new function `bidi-find-overridden-directionality' allows to
 find characters whose directionality was, perhaps maliciously,
@@ -1199,6 +1182,26 @@ evaluated (and should return a string) when the closure is built.
 ** New function `string-greaterp', which return the opposite result of
 `string-lessp'.
 
++++
+** The new functions `string-collate-lessp' and `string-collate-equalp'
+preserve the collation order as defined by the system's locale(1)
+environment.  For the time being this is implemented for modern POSIX
+systems and for MS-Windows, for other systems they fall back to their
+counterparts `string-lessp' and `string-equal'.
+
+---
+*** The ls-lisp package uses `string-collate-lessp' to sort file names.
+If you want the old, locale-independent sorting, customize the new
+option `ls-lisp-use-string-collate' to a nil value.
+
++++
+*** The MS-Windows specific variable `w32-collate-ignore-punctuation',
+if set to a non-nil value, causes the above 2 functions to ignore
+symbol and punctuation characters when collating strings.  This
+emulates the behavior of modern Posix platforms when the locale's
+codeset is "UTF-8" (as in "en_US.UTF-8").  This is needed because
+MS-Windows doesn't support UTF-8 as codeset in its locales.
+
 ** New function `alist-get', which is also a valid place (aka lvalue).
 
 ** New function `funcall-interactively', which works like `funcall'