(ssadd [ename [sname]])
The ssadd function adds a valid entity specified by ename to an existing selection set specified by sname, or it creates a new selection set. The function returns a new selection set.
The entity specified by ename and the selection set sname must belong to the current drawing.
Entering ssadd with no argument returns a new, empty selection set.
Entering ssadd with a valid entity name, but without the argument sname, creates a new selection set containing the single entity ename.
As in ename a valid entity name and in sname a valid selection set name is provided, the entity ename is added to selection set.
If the function fails, it returns nil.
Examples
: (setq as (ssadd))
<Selset: 3d671828:00000006>
: (ssadd (entlast) as)
<Selset: 3d671828:00000006>