Deletes an object (entity) from a selection set
(ssdel enamess)
The name of the selection set; otherwise nil, if the specified entity is not in the set.
Note that the entity is actually deleted from the existing selection set, as opposed to a new set being returned with the element deleted.
In the following examples, entity name e1 is a member of selection set ss, while entity name e3 is not a member of ss:
Command: (ssdel e1 ss)
<Selection set: 2>
Selection set ss is returned with entity e1 removed.
Command: (ssdel e3 ss)
nil
The function returns nil because e3 is not a member of selection set ss.