diff --git a/user_guide_src/source/incoming/routing.rst b/user_guide_src/source/incoming/routing.rst
index dc27a5aeb8e3..9a206e7b096d 100644
--- a/user_guide_src/source/incoming/routing.rst
+++ b/user_guide_src/source/incoming/routing.rst
@@ -77,7 +77,7 @@ Placeholders Description
 ============ ===========================================================================================================
 
 .. note:: ``{locale}`` cannot be used as a placeholder or other part of the route, as it is reserved for use
-    in :doc:`localization </outgoing/localization>`.
+    in :doc:`localization </outgoing/localization>` (see also :ref:`locale-placeholder`).
 
 Examples
 ========
@@ -145,6 +145,19 @@ In such a case, you can specify the parameters manually:
 .. literalinclude:: routing/016.php
    :lines: 2-
 
+.. _locale-placeholder:
+
+Locale Placeholder
+==================
+
+The placeholder ``{locale}`` is a reserved placeholder that is used in :doc:`localization </outgoing/localization>`
+and has the following Regular Expression pattern ``[^/]+``.
+
+You can override the default pattern with the ``setLocalePattern()`` method. The parameter is the Regular Expression
+pattern it should be replaced with:
+
+.. literalinclude:: routing/053.php
+
 Custom Placeholders
 ===================
 
diff --git a/user_guide_src/source/incoming/routing/053.php b/user_guide_src/source/incoming/routing/053.php
new file mode 100644
index 000000000000..5348dad4ed4c
--- /dev/null
+++ b/user_guide_src/source/incoming/routing/053.php
@@ -0,0 +1,3 @@
+<?php
+
+$routes->setLocalePattern('[a-z]{2}[_-][A-Z]{2}');