(defun collinear (line1 line2 fuzz / p1 p2)
   (if (= (type line1) 'ENAME)
      (setq line1 (vlax-ename->vla-object line1))
   )
   (if (= (type line2) 'ENAME)
      (setq line2 (vlax-ename->vla-object line2))
   )
   (and
      (= (type line1) 'VLA-OBJECT)
      (= (type line2) 'VLA-OBJECT)
      (= (vlax-get line1 "ObjectName") "AcDbLine")
      (= (vlax-get line2 "ObjectName") "AcDbLine")
      (setq p1 (vlax-get line1 "StartPoint"))
      (setq p2 (vlax-get line1 "EndPoint"))
      (numberp fuzz)
      (equal (vlax-curve-getClosestPointTo line2 p1 T) p1 fuzz)
      (equal (vlax-curve-getClosestPointTo line2 p2 T) p2 fuzz)
   )
)
(defun c:collinear ( / e1 e2)
   (if (and (setq e1 (car (entsel "\nSelect 1st line: ")))
            (setq e2 (car (entsel "\nSelect 2nd line: ")))
            (setq fuzz (getdist "\nFuzz factor: "))
       )
      (collinear e1 e2 fuzz)
   )
)