diff --git a/reference/array/functions/array-column.xml b/reference/array/functions/array-column.xml
index c5435e4fd4..c656fc6b13 100644
--- a/reference/array/functions/array-column.xml
+++ b/reference/array/functions/array-column.xml
@@ -41,7 +41,8 @@
       <para>
        The column of values to return. This value may be the integer key of the
        column you wish to retrieve, or it may be the string key name for an
-       associative array.
+       associative array. It may also be &null; to return comlete arrays (useful
+       together with <parameter>index_key</parameter> to reindex the array).
       </para>
      </listitem>
     </varlistentry>