diff --git a/reference/forms/types/form.rst b/reference/forms/types/form.rst
index 4a99b6e55d8..39d22ccaa0e 100644
--- a/reference/forms/types/form.rst
+++ b/reference/forms/types/form.rst
@@ -41,6 +41,8 @@ on all fields.
 
 .. include:: /reference/forms/types/options/block_name.rst.inc
 
+.. include:: /reference/forms/types/options/max_length.rst.inc
+
 inherit_data
 ------------
 
diff --git a/reference/forms/types/options/max_length.rst.inc b/reference/forms/types/options/max_length.rst.inc
index ef0a487e473..d20d44e1199 100644
--- a/reference/forms/types/options/max_length.rst.inc
+++ b/reference/forms/types/options/max_length.rst.inc
@@ -1,7 +1,10 @@
 max_length
 ~~~~~~~~~~
 
-**type**: ``integer``
+**type**: ``integer`` **default**: ``null``
 
-This option is used to add a ``maxlength`` attribute, which is used by
-some browsers to limit the amount of text in a field.
+If this option is not null, an attribute ``maxlength`` is added, which 
+is used by some browsers to limit the amount of text in a field. 
+
+This is just a browser validation, so data must still be validated 
+server-side.