The usual...
diff --git a/Lib/dos-8x3/regex_sy.py b/Lib/dos-8x3/regex_sy.py
index 8631f42..aab7e7a 100755
--- a/Lib/dos-8x3/regex_sy.py
+++ b/Lib/dos-8x3/regex_sy.py
@@ -1,5 +1,11 @@
-# These bits are passed to regex.set_syntax() to choose among
-# alternative regexp syntaxes.
+"""Constants for selecting regexp syntaxes for the obsolete regex module.
+
+This module is only for backward compatibility. "regex" has now
+been replaced by the new regular expression module, "re".
+
+These bits are passed to regex.set_syntax() to choose among
+alternative regexp syntaxes.
+"""
# 1 means plain parentheses serve as grouping, and backslash
# parentheses are needed for literal searching.