请教尺寸箭头问题！

龙龙仔

;;只对线性标註有效
;;BY 龙龙仔(LUCAS)
(defun C:BLKCH (/ A E1 PT D1 D2 WHICH)
(setq A (entsel "\n选取边: "))
(setq PT (trans (cadr A) 1 0))
(setq E1 (entget (car A)))
(setq D1 (distance PT (cdr (assoc 13 E1))))
(setq D2 (distance PT (cdr (assoc 14 E1))))
(cond
((> D1 D2) (setq WHICH "DIMBLK2"))
((> D2 D1) (setq WHICH "DIMBLK1"))
(t NIL)
)
(command "_.dimoverride" "DIMSAH" 1 WHICH "_DOTSMALL" "" A "")
(princ)
)