Method of creating dropdown box for a domainname in APS package ?

in service settings tab create a field with the follwing values

ID- domainname
Name- Domain Name
Class-domain-name
Element type-domain name
Minterms-1
Maxterms-1

here customer can select add only one domain because minterms and maxterms entered as 1.

or else you  can use only ID,Name,class=domain-name this also work fields like

Element type-domain name
Minterms-1
Maxterms-1

are not mandatory