<rng:optional> <rng:attribute name="target"/> </rng:optional>
<rng:optional> <rng:attribute name="key2"/> </rng:optional>
<rng:optional> <rng:attribute name="groups"/> </rng:optional>
+ <rng:optional> <rng:attribute name="limit"/> </rng:optional>
+ <rng:optional> <rng:attribute name="usage"/> </rng:optional>
+ <rng:optional> <rng:attribute name="auto_refresh"/> </rng:optional>
<rng:empty />
</rng:element>
</rng:define>