(defun toggleBackgroundMaskOfAMText (en / ed) 
  (setq ed (entget en))   ; Sets ed to the entity data 
  (setq atom90 (assoc 90 ed)) 
  (if (= atom90 nil) 
    ;; no 90 groud code at all 
    (progn 
      (setq lst90 (cons 90 1)) 
      (setq atom63 (cons 63 1)) 
      (setq ed (append ed (list atom63 lst90))) 
      ;; Add the 63 group code to set the background color as 1 (RED) 
    ) 
    (progn 
      (setq maskProp (cdr atom90)) 
      (if (= (boole 1 maskProp 1) 1) 
(setq new90 (cons 90 2)) 
(setq new90 (cons 90 1)) 
      ) 
      (setq ed 
      (subst new90 
      (assoc 90 ed) ; Toggle the value of 90 group in ed. 
      ed 
      ) 
      ) 
    ) 
  )

  (entmod ed) 
  (princ) 
)