#5241: document missing U in regex howto.
diff --git a/Doc/howto/regex.rst b/Doc/howto/regex.rst
index 994c0b9..eab23af 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:`UNICODE`, :const:`U` | Makes several escapes like ``\w``, ``\b``, |
+| | ``\s`` and ``\d`` dependent on the Unicode |
+| | character database. |
++---------------------------------+--------------------------------------------+
.. data:: I
@@ -594,6 +598,14 @@
newline; without this flag, ``'.'`` will match anything *except* a newline.
+.. data:: U
+ UNICODE
+ :index:
+
+ Make ``\w``, ``\W``, ``\b``, ``\B``, ``\d``, ``\D``, ``\s`` and ``\S``
+ dependent on the Unicode character properties database.
+
+
.. data:: X
VERBOSE
:noindex: