diff --git a/reference/pdo_4d/sql4d.xml b/reference/pdo_4d/sql4d.xml
index e9d64c657e..991459acfc 100644
--- a/reference/pdo_4d/sql4d.xml
+++ b/reference/pdo_4d/sql4d.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<!-- $Revision: 1.5 $ -->
+<!-- $Revision: 1.6 $ -->
 
 <refentry xml:id="ref.pdo-4d.sql4d" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
  <refnamediv>
@@ -85,6 +85,17 @@
          and <literal>_USER_SCHEMAS</literal>.
         </entry>
        </row>
+       <row>
+        <entry>SQL structure delimiter</entry>
+        <entry>To escape SQL elements (tables, fields, users, groups, schema,
+        primary key, etc.), closing brackets must be doubled, and the whole 
+        identifier must be between square brackets.
+        <entry>
+         Use the following function to protect SQL objects, and then,
+         put it between square brackets : 
+         <literal>str_replace(']',']]', $table)</literal>.
+        </entry>
+       </row>
       </tbody>
      </tgroup>
     </table>