diff --git a/modules/mol/base/doc/entity.rst b/modules/mol/base/doc/entity.rst
index f08dfe9352e6bae2dbf94e2a0cca6e9a2290f0de..4d9f7733d7244a87f0492e567eb16d1a752ab8dc 100644
--- a/modules/mol/base/doc/entity.rst
+++ b/modules/mol/base/doc/entity.rst
@@ -2032,6 +2032,7 @@ ChemClass
     * ``WATER``             = 'W'
     * ``UNKNOWN``           = 'U'
 
+  The constants are defined directly within the :mod:`mol` module.
   Python can implicitly convert characters to objects of this type. Note however
   that only the first character of a :class:`str` object is considered!