;; | ----------------------------------------------------------------------------
;; | SS_SSjoin
;; | ----------------------------------------------------------------------------
;; | Function : Joins two selections set and returns their sum
;; | Arguments:
;; |            'ss1'    - First Selection set (overloaded - can be entity
;; |                       name as well)
;; |            'ss2'    - Second Selection set (overloaded - can be entity
;; |                       name as well)
;; | Return   : The difference selection set
;; | Updated  : April 24, 1998
;; | e-mail   : rakesh.rao@4d-technologies.com 
;; | Web      : www.4d-technologies.com
;; | ----------------------------------------------------------------------------

(defun SS_SSjoin ( ss1 ss2 / ename ss cnt )

(if ss1
(progn
	(if (= (type ss1) 'ENAME)
	(progn
		(setq
			ename ss1
			ss1   (ssadd)
		)
		(ssadd ename ss1)
	))
))

(if ss2
(progn
	(if (= (type ss2) 'ENAME)
	(progn
		(setq
			ename ss2
			ss2   (ssadd)
		)
		(ssadd ename ss2)
	))
))

(setq ss (ssadd))

(if (and ss1 ss2)
(progn
	(setq ss ss2 cnt 0)
	(repeat (sslength ss1)
		(ssadd (ssname ss1 cnt) ss)
		(setq cnt (1+ cnt))
	)
))

(if (and ss1 (not ss2))
(setq ss ss1))

(if (and ss2 (not ss1))
(setq ss ss2))

(if (> (sslength ss) 0)
	(eval ss)
	nil
)
)