--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2008-01-10  Bruno Haible  <bruno@clisp.org>
+
+	* doc/gnulib.texi (String Functions in C Locale): New section.
+	* doc/c-ctype.texi: New file.
+	* doc/c-strcase.texi: New file.
+	* doc/c-strcaseeq.texi: New file.
+	* doc/c-strcasestr.texi: New file.
+	* doc/c-strstr.texi: New file.
+	* doc/c-strtod.texi: New file.
+	* doc/c-strtold.texi: New file.
+
 2008-01-10  Eric Blake  <ebb9@byu.net>
 
 	* lib/relocatable.h: Fix a comment.

new file mode 100644
--- /dev/null
+++ b/doc/c-ctype.texi
@@ -0,0 +1,47 @@
+@c Documentation of gnulib module 'c-ctype'.
+
+@c Copyright (C) 2008 Free Software Foundation, Inc.
+
+@c Permission is granted to copy, distribute and/or modify this document
+@c under the terms of the GNU Free Documentation License, Version 1.2 or
+@c any later version published by the Free Software Foundation; with no
+@c Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+@c Texts.  A copy of the license is included in the ``GNU Free
+@c Documentation License'' file as part of this distribution.
+
+The @code{c-ctype} module contains functions operating on single-byte
+characters, like the functions in @code{<ctype.h>}, that operate as if the
+locale encoding was ASCII.  (The "C" locale on many systems has the locale
+encoding "ASCII".)
+
+The functions are:
+@smallexample
+extern bool c_isascii (int c);
+
+extern bool c_isalnum (int c);
+extern bool c_isalpha (int c);
+extern bool c_isblank (int c);
+extern bool c_iscntrl (int c);
+extern bool c_isdigit (int c);
+extern bool c_islower (int c);
+extern bool c_isgraph (int c);
+extern bool c_isprint (int c);
+extern bool c_ispunct (int c);
+extern bool c_isspace (int c);
+extern bool c_isupper (int c);
+extern bool c_isxdigit (int c);
+
+extern int c_tolower (int c);
+extern int c_toupper (int c);
+@end smallexample
+
+These functions assign properties only to ASCII characters.
+
+The @var{c} argument can be a @code{char} or @code{unsigned char} value,
+whereas the corresponding functions in @code{<ctype.h>} take an argument
+that is actually an @code{unsigned char} value.
+
+The @code{c_is*} functions return @samp{bool}, where the corresponding
+functions in @code{<ctype.h>} return @samp{int} for historical reasons.
+
+Note: The @code{<ctype.h>} functions support only unibyte locales.

new file mode 100644
--- /dev/null
+++ b/doc/c-strcase.texi
@@ -0,0 +1,29 @@
+@c Documentation of gnulib module 'c-strcase'.
+
+@c Copyright (C) 2008 Free Software Foundation, Inc.
+
+@c Permission is granted to copy, distribute and/or modify this document
+@c under the terms of the GNU Free Documentation License, Version 1.2 or
+@c any later version published by the Free Software Foundation; with no
+@c Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+@c Texts.  A copy of the license is included in the ``GNU Free
+@c Documentation License'' file as part of this distribution.
+
+The @code{c-strcase} module contains case-insensitive string comparison
+functions operating on single-byte character strings, like the functions in
+@code{<strings.h>}, that operate as if the locale encoding was ASCII.
+(The "C" locale on many systems has the locale encoding "ASCII".)
+
+The functions are:
+@smallexample
+extern int c_strcasecmp (const char *s1, const char *s2);
+extern int c_strncasecmp (const char *s1, const char *s2, size_t n);
+@end smallexample
+
+For case conversion here, only ASCII characters are considered to be
+upper case or lower case.
+
+Note: The functions @code{strcasecmp}, @code{strncasecmp} from
+@code{<strings.h>} support only unibyte locales; for multibyte locales,
+you need the functions @code{mbscasecmp}, @code{mbsncasecmp},
+@code{mbspcasecmp}.

new file mode 100644
--- /dev/null
+++ b/doc/c-strcaseeq.texi
@@ -0,0 +1,28 @@
+@c Documentation of gnulib module 'c-strcaseeq'.
+
+@c Copyright (C) 2008 Free Software Foundation, Inc.
+
+@c Permission is granted to copy, distribute and/or modify this document
+@c under the terms of the GNU Free Documentation License, Version 1.2 or
+@c any later version published by the Free Software Foundation; with no
+@c Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+@c Texts.  A copy of the license is included in the ``GNU Free
+@c Documentation License'' file as part of this distribution.
+
+The @code{c-strcaseeq} module contains an optimized case-insensitive
+string comparison function operating on single-byte character strings, that
+operate as if the locale encoding was ASCII.
+(The "C" locale on many systems has the locale encoding "ASCII".)
+
+The functions is actually implemented as a macro:
+@smallexample
+extern int STRCASEEQ (const char *s1, const char *s2,
+                      int s20, int s21, int s22, int s23, int s24, int s25,
+                      int s26, int s27, int s28);
+@end smallexample
+
+@var{s2} should be a short literal ASCII string, and @var{s20}, @var{s21}, ...
+the individual characters of @var{s2}.
+
+For case conversion here, only ASCII characters are considered to be
+upper case or lower case.

new file mode 100644
--- /dev/null
+++ b/doc/c-strcasestr.texi
@@ -0,0 +1,27 @@
+@c Documentation of gnulib module 'c-strcasestr'.
+
+@c Copyright (C) 2008 Free Software Foundation, Inc.
+
+@c Permission is granted to copy, distribute and/or modify this document
+@c under the terms of the GNU Free Documentation License, Version 1.2 or
+@c any later version published by the Free Software Foundation; with no
+@c Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+@c Texts.  A copy of the license is included in the ``GNU Free
+@c Documentation License'' file as part of this distribution.
+
+The @code{c-strcasestr} module contains a case-insensitive string search
+function operating on single-byte character strings, that operate as if the
+locale encoding was ASCII.
+(The "C" locale on many systems has the locale encoding "ASCII".)
+
+The function is:
+@smallexample
+extern char *c_strcasestr (const char *haystack, const char *needle);
+@end smallexample
+
+For case conversion here, only ASCII characters are considered to be
+upper case or lower case.
+
+Note: The function @code{strcasestr} from @code{<string.h>} supports only
+unibyte locales; for multibyte locales, you need the function
+@code{mbscasestr}.

new file mode 100644
--- /dev/null
+++ b/doc/c-strstr.texi
@@ -0,0 +1,24 @@
+@c Documentation of gnulib module 'c-strstr'.
+
+@c Copyright (C) 2008 Free Software Foundation, Inc.
+
+@c Permission is granted to copy, distribute and/or modify this document
+@c under the terms of the GNU Free Documentation License, Version 1.2 or
+@c any later version published by the Free Software Foundation; with no
+@c Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+@c Texts.  A copy of the license is included in the ``GNU Free
+@c Documentation License'' file as part of this distribution.
+
+The @code{c-strstr} module contains a substring search function operating
+on single-byte character strings, that operate as if the locale encoding
+was ASCII.
+(The "C" locale on many systems has the locale encoding "ASCII".)
+
+The function is:
+@smallexample
+extern char *c_strstr (const char *haystack, const char *needle);
+@end smallexample
+
+Note: The function @code{strstr} from @code{<string.h>} supports only
+unibyte locales; for multibyte locales, you need the function
+@code{mbsstr}.

new file mode 100644
--- /dev/null
+++ b/doc/c-strtod.texi
@@ -0,0 +1,23 @@
+@c Documentation of gnulib module 'c-strtod'.
+
+@c Copyright (C) 2008 Free Software Foundation, Inc.
+
+@c Permission is granted to copy, distribute and/or modify this document
+@c under the terms of the GNU Free Documentation License, Version 1.2 or
+@c any later version published by the Free Software Foundation; with no
+@c Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+@c Texts.  A copy of the license is included in the ``GNU Free
+@c Documentation License'' file as part of this distribution.
+
+The @code{c-strtod} module contains a string to number (@samp{double})
+conversion function operating on single-byte character strings, that operates
+as if the locale encoding was ASCII.
+(The "C" locale on many systems has the locale encoding "ASCII".)
+
+The function is:
+@smallexample
+extern double c_strtod (const char *string, char **endp);
+@end smallexample
+
+In particular, only a period @samp{.} is accepted as decimal point, even
+when the current locale's notion of decimal point is a comma @samp{,}.

new file mode 100644
--- /dev/null
+++ b/doc/c-strtold.texi
@@ -0,0 +1,23 @@
+@c Documentation of gnulib module 'c-strtold'.
+
+@c Copyright (C) 2008 Free Software Foundation, Inc.
+
+@c Permission is granted to copy, distribute and/or modify this document
+@c under the terms of the GNU Free Documentation License, Version 1.2 or
+@c any later version published by the Free Software Foundation; with no
+@c Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+@c Texts.  A copy of the license is included in the ``GNU Free
+@c Documentation License'' file as part of this distribution.
+
+The @code{c-strtold} module contains a string to number (@samp{long double})
+conversion function operating on single-byte character strings, that operates
+as if the locale encoding was ASCII.
+(The "C" locale on many systems has the locale encoding "ASCII".)
+
+The function is:
+@smallexample
+extern long double c_strtold (const char *string, char **endp);
+@end smallexample
+
+In particular, only a period @samp{.} is accepted as decimal point, even
+when the current locale's notion of decimal point is a comma @samp{,}.

--- a/doc/gnulib.texi
+++ b/doc/gnulib.texi
@@ -2895,6 +2895,7 @@
 @menu
 * alloca::
 * alloca-opt::
+* String Functions in C Locale::
 * Quoting::
 * error and progname::
 * gcd::
@@ -2912,6 +2913,58 @@
 @findex alloca
 @include alloca-opt.texi
 
+@node String Functions in C Locale
+@section Character and String Functions in C Locale
+
+The functions in this section are similar to the generic string functions
+from the standard C library, except that
+@itemize
+@item
+They behave as if the locale was set to the "C" locale, even when the
+locale is different, and/or
+@item
+They are specially optimized for the case where all characters are plain
+ASCII characters.
+@end itemize
+
+@menu
+* c-ctype::
+* c-strcase::
+* c-strcaseeq::
+* c-strcasestr::
+* c-strstr::
+* c-strtod::
+* c-strtold::
+@end menu
+
+@node c-ctype
+@subsection c-ctype
+@include c-ctype.texi
+
+@node c-strcase
+@subsection c-strcase
+@include c-strcase.texi
+
+@node c-strcaseeq
+@subsection c-strcaseeq
+@include c-strcaseeq.texi
+
+@node c-strcasestr
+@subsection c-strcasestr
+@include c-strcasestr.texi
+
+@node c-strstr
+@subsection c-strstr
+@include c-strstr.texi
+
+@node c-strtod
+@subsection c-strtod
+@include c-strtod.texi
+
+@node c-strtold
+@subsection c-strtold
+@include c-strtold.texi
+
 @include quote.texi
 @include error.texi
 @include gcd.texi