Added a note that these are not available under Carbon (or
OSX MachO Python).
diff --git a/Doc/mac/libctb.tex b/Doc/mac/libctb.tex
index 2cb2b03..9950a41 100644
--- a/Doc/mac/libctb.tex
+++ b/Doc/mac/libctb.tex
@@ -9,7 +9,10 @@
 
 This module provides a partial interface to the Macintosh
 Communications Toolbox. Currently, only Connection Manager tools are
-supported.  It may not be available in all Mac Python versions.
+supported.
+
+This module is only available under MacOS9 or earlier, in classic PPC
+MacPython.
 \index{Communications Toolbox, Macintosh}
 \index{Macintosh Communications Toolbox}
 \index{Connection Manager}