--- a/Doc/api/api.tex	Wed Sep 05 15:44:37 2001 +0000
+++ b/Doc/api/api.tex	Wed Sep 05 17:09:48 2001 +0000
@@ -3020,7 +3020,11 @@
 as the ones of the builtin unicode() Unicode object constructor.
 
 Setting encoding to NULL causes the default encoding to be used which
-is UTF-8.
+is \ASCII{}. The file system calls should use
+\var{Py_FileSystemDefaultEncoding} as the encoding for file
+names. This variable should be treated as read-only: On some systems,
+it will be a pointer to a static string, on others, it will change at
+run-time, e.g. when the application invokes setlocale.
 
 Error handling is set by errors which may also be set to NULL meaning
 to use the default handling defined for the codec. Default error