Document _toupper(3) and _tolower(3) and mention XPG4.2.

1 files changed, 27 insertions, 9 deletions

diff --git a/lib/libc/gen/tolower.3 b/lib/libc/gen/tolower.3
index e3320397980..d1de787b368 100644
--- a/lib/libc/gen/tolower.3
+++ b/lib/libc/gen/tolower.3
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: tolower.3,v 1.3 1996/11/02 00:12:57 deraadt Exp $
+.\"	$OpenBSD: tolower.3,v 1.4 1997/08/16 05:58:19 millert Exp $
 .\"
 .\" Copyright (c) 1989, 1991 The Regents of the University of California.
 .\" All rights reserved.
@@ -35,26 +35,39 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd June 29, 1991
+.Dd August 15, 1997
 .Dt TOLOWER 3
 .Os
 .Sh NAME
-.Nm tolower
+.Nm tolower ,
+.Nm _tolower
 .Nd upper case to lower case letter conversion
 .Sh SYNOPSIS
 .Fd #include <ctype.h>
 .Ft int
 .Fn tolower "int c"
+.Ft int
+.Fn _tolower "int c"
 .Sh DESCRIPTION
 The
 .Fn tolower
 function converts an upper-case letter to the corresponding lower-case
-letter.
+letter.  The
+.Fn _tolower
+function is identical to
+.Fn tolower
+except that
+.Ar c
+must be an upper-case letter.
 .Sh RETURN VALUES
-If the argument is an upper-case letter, the
+If the argument to the
 .Fn tolower
-function returns the corresponding lower-case letter if there is
-one; otherwise the argument is returned unchanged.
+function is an upper-case letter, the corresponding lower-case letter
+is returned if there is one; otherwise the argument is returned unchanged.
+If the argument to the
+.Fn _tolower
+function is an upper-case letter, the corresponding lower-case letter
+is returned; otherwise the output is undefined.
 .\" In the 
 .\" .Em ``C''
 .\" locale,
@@ -79,10 +92,15 @@ one; otherwise the argument is returned unchanged.
 .Xr isxdigit 3 ,
 .Xr toascii 3 ,
 .Xr toupper 3 ,
+.Xr _toupper 3 ,
 .Xr stdio 3 ,
 .Xr ascii 7
 .Sh STANDARDS
 The
 .Fn tolower
-function conforms to
-.St -ansiC .
+and
+.Fn _tolower
+functions conform to
+.St -ansiC
+and
+.St -xpg4.2 .