diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 4d1fbb581f..bec2067707 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,8 @@
+2002-06-25  Don Howard  <dhoward@redhat.com>
+
+	* gdb.texinfo (Memory Region Attributes): Document new behavior
+	for 'mem' command.
+
 2002-06-11  Jim Blandy  <jimb@redhat.com>
 
 	* gdb.texinfo (Symbols): Update documentation for `info source'
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index aa39d76753..6d725ed73d 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -5601,9 +5601,11 @@ to enable, disable, or remove a memory region, you specify that number.
 
 @table @code
 @kindex mem
-@item mem @var{address1} @var{address2} @var{attributes}@dots{}
-Define memory region bounded by @var{address1} and @var{address2}
-with attributes @var{attributes}@dots{}.
+@item mem @var{lower} @var{upper} @var{attributes}@dots{}
+Define memory region bounded by @var{lower} and @var{upper} with
+attributes @var{attributes}@dots{}.  Note that @var{upper} == 0 is a
+special case: it is treated as the the target's maximum memory address.
+(0xffff on 16 bit targets, 0xffffffff on 32 bit targets, etc.)
 
 @kindex delete mem
 @item delete mem @var{nums}@dots{}