; 16-Feb-09 NEHolt created 
(defun c:r90 ( / x en ed x50 newed)
  ; Purpose: rotate leader MTEXT in 90 degree increments
  (while (setq x (entsel "\nSelect wire color/ga label:"))
    (setq en (car x)) ; get selected entity name
    (setq ed (entget en)) ; read the entity's data
    ; make sure it's MTEXT entity
    (if (= (cdr (assoc 0 ed)) "MTEXT") 
      (progn ; okay to continue. 
        ; Rotate MTEXT by 90 degrees. Get current rotation
        (setq x50 (cdr (assoc 50 ed))) ; (in radians)
        ; Add "(* pi 0.5)" radians (or "90" degrees)
        (setq x50 (+ x50 (* pi 0.5)))
        ; Substitute new value into copy of entity's data
        (setq newed (subst (cons 50 x50)(assoc 50 ed) ed))
        ; Write new version of entity's data back
        (if newed (entmod newed))
        (entupd en) 
        (command "_.REGEN") ; force display to update
    ) )
  )
  (princ) ; quiet / clean exit
)
(princ "Type R90 [Enter] to run this utility")(princ)