diff --git a/reference/forms/types/form.rst b/reference/forms/types/form.rst
index dfe67119f6c..43ab188086a 100644
--- a/reference/forms/types/form.rst
+++ b/reference/forms/types/form.rst
@@ -59,3 +59,8 @@ on all fields.
 
 .. include:: /reference/forms/types/options/invalid_message_parameters.rst.inc
 
+.. include:: /reference/forms/types/options/extra_fields_message.rst.inc
+
+.. include:: /reference/forms/types/options/post_max_size_message.rst.inc
+
+.. include:: /reference/forms/types/options/pattern.rst.inc
diff --git a/reference/forms/types/options/extra_fields_message.rst.inc b/reference/forms/types/options/extra_fields_message.rst.inc
new file mode 100644
index 00000000000..d130808191c
--- /dev/null
+++ b/reference/forms/types/options/extra_fields_message.rst.inc
@@ -0,0 +1,9 @@
+extra_fields_message
+~~~~~~~~~~~~~~~~~~~~
+
+**type**: ``string`` **default**: ``This form should not contain extra fields.``
+
+This is the validation error message that's used if the submitted form data
+contains one or more fields that are not part of the form definition. The
+placeholder ``{{ extra_fields }}`` can be used to display a comma separated
+list of the submitted extra field names.
diff --git a/reference/forms/types/options/pattern.rst.inc b/reference/forms/types/options/pattern.rst.inc
new file mode 100644
index 00000000000..d1ff3aea732
--- /dev/null
+++ b/reference/forms/types/options/pattern.rst.inc
@@ -0,0 +1,18 @@
+pattern
+~~~~~~~
+
+**type**: ``string`` **default**: ``null``
+
+This adds an HTML5 ``pattern`` attribute to restrict the field input by a
+given regular expression.
+
+.. caution:
+
+    The ``pattern`` attribute provides client-side validation for convenience
+    purposes only and must not be used as a replacement for reliable
+    server-side validation.
+
+.. note:
+
+    When using validation constraints, this option is set automatically
+    for some constraints to match the server-side validation.
diff --git a/reference/forms/types/options/post_max_size_message.rst.inc b/reference/forms/types/options/post_max_size_message.rst.inc
new file mode 100644
index 00000000000..f85cb83a99d
--- /dev/null
+++ b/reference/forms/types/options/post_max_size_message.rst.inc
@@ -0,0 +1,12 @@
+post_max_size_message
+~~~~~~~~~~~~~~~~~~~~~
+
+**type**: ``string`` **default**: ``The uploaded file was too large. Please try to upload a smaller file.``
+
+This is the validation error message that's used if submitted POST form data
+exceeds ``php.ini``'s ``post_max_size`` directive. The ``{{ max }}``
+placeholder can be used to display the allowed size.
+
+.. note:
+
+    Validating the ``post_max_size`` only happens on the root form.