+</programlisting>
+ </para></listitem>
+
+ <listitem><para>
+ For a similar reason, any tag used in the filter argument will <emphasis>have to</emphasis> be mentioned in the list of returned columns as well. For example:
+<programlisting>
+# if 'hrn' is not part of the result, this does not work
+>>> ns=GetNodes({'hrn':'ple.*'},['hostname'])
+Database error b59e068c-589a-4ad5-9dd8-63cc38f2a2eb:
+column "hrn" does not exist
+LINE 1: ...M view_nodes WHERE deleted IS False AND (True AND hrn ILIKE ...
+... abridged ...
+# this can be worked around by just returning 'hrn' as well
+>>> ns=GetNodes({'hrn':'ple.*'},['hrn','hostname'])