#5241: document missing A in regex howto.
diff --git a/Doc/howto/regex.rst b/Doc/howto/regex.rst
index 3ed5368..2623867 100644
--- a/Doc/howto/regex.rst
+++ b/Doc/howto/regex.rst
@@ -540,6 +540,10 @@
| :const:`VERBOSE`, :const:`X` | Enable verbose REs, which can be organized |
| | more cleanly and understandably. |
+---------------------------------+--------------------------------------------+
+| :const:`ASCII`, :const:`A` | Makes several escapes like ``\w``, ``\b``, |
+| | ``\s`` and ``\d`` match only on ASCII |
+| | characters with the respective property. |
++---------------------------------+--------------------------------------------+
.. data:: I
@@ -594,6 +598,15 @@
newline; without this flag, ``'.'`` will match anything *except* a newline.
+.. data:: A
+ ASCII
+ :noindex:
+
+ Make ``\w``, ``\W``, ``\b``, ``\B``, ``\s`` and ``\S`` perform ASCII-only
+ matching instead of full Unicode matching. This is only meaningful for
+ Unicode patterns, and is ignored for byte patterns.
+
+
.. data:: X
VERBOSE
:noindex: