Hi Nidhi,
For instance, in nms:deliveryDet form definition, you can find this reference used:
ref="nms:delivery:lib/summary"
It follows the XPATH syntax after the space name:form name.
and so, you can find the XML code definition in the nms:delivery form definition:
<container img="nms:delivery.png" label="Résumé" name="summary">
which is defined for:
<container name="lib" type="visibleGroup" visibleIf="false">
In your case you should find a "file" / line in Input form list adi:delivery, and look for delivery container definition.
Hope this helps.
Regards.
J-Serge