diff --git a/reference/componere/book.xml b/reference/componere/book.xml
index 8ae969d62d..286153b3f0 100644
--- a/reference/componere/book.xml
+++ b/reference/componere/book.xml
@@ -34,9 +34,14 @@
     <title>Casting:</title>
     <para>
      <classname>Componere\</classname> casting functions can cast among user defined compatible types;
-     Where compatible means <classname>Type</classname> is contravariant or covariant with the class of <parameter>object</parameter>.
+     Where compatible means <classname>Type</classname> is a sub type or super type of <parameter>object</parameter>.
      <xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('componere.cast')/db:refsect1[@role='description']/descendant::db:methodsynopsis)" />
      <xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('componere.cast_by_ref')/db:refsect1[@role='description']/descendant::db:methodsynopsis)" />
+     <note>
+      <para>
+       Casting can not be performed losslessly: The result of a cast cannot be cast back to it's original class without loss, incurred at the point of the original cast.
+      </para>
+     </note>
     </para>
   </formalpara>