Tests whether an object (entity) is a member of a selection set
(ssmemb enamess)
If ename is a member of ss, ssmemb returns the entity name. If ename is not a member, ssmemb returns nil.
In the following examples, entity name e2 is a member of selection set ss, while entity name e1 is not a member of ss:
Command: (ssmemb e2 ss)
<Entity name: 1d62d68>
Command: (ssmemb e1 ss)
nil