diff --git a/xdoc/xdocs/properties.xml b/xdoc/xdocs/properties.xml
index f2e177ee..9fea1d36 100644
--- a/xdoc/xdocs/properties.xml
+++ b/xdoc/xdocs/properties.xml
@@ -180,6 +180,7 @@
                 Sets the default locale used for the translation. If null, it is
                 the default locale for this instance of the Java Virtual Machine
                 Defaults to "en", ie english, to ensure backwards compatibility.
+                Be careful, following the standard, this value is case sensitive.
             </td>
         </tr>
         <tr>