(defun c:BlkDescLink (/ d)
  
  (if (and
        (or (and
              (setq ss (ssget "_i")) (= 1 (sslength ss)) (setq d (ssname ss 0))
            )
            (setq d (car(entsel)))
        )
        (= "INSERT" (cdr(assoc 0 (setq d (entget d)))))
      )
      (startapp "Explorer" (cdr(assoc 4 (entget(tblobjname "BLOCK" (cdr(assoc 2 d)))))))
  )
  
)