It doesn't ask you for it?
It's quite easy to get a bit fed up with the interfaces they provide. They need your name server name, ns1.xyz.org and they're supposed to ask for, or have a place to enter, Glue. Glue is the Host (A) record associated with the name server and will be added to the parent DNS servers (.org).
Is there any mention of glue anywhere in the interface?
Chris