/*
   Cycle between styles.  If there were 5 styles:
   To go to the next style:  (style//stylect) + 1:
          1   2   3   4   5
          1   2   3   4   0    (mod stylect)
          2   3   4   5   1    (add one)
   To go to the prior style:  (style+stylect-2)//stylect + 1
          1   2   3   4   5
          6   7   8   9  10    (+stylect)
          4   5   6   7   8    ( -2 )
          4   0   1   2   3    ( //stylect)
          5   1   2   3   4    ( +1 )
   This works regardless of the number of styles; it even works when
   the number of styles is 1!
.  ----------------------------------------------------------------- */
BRDK_CHECK_STYLE:                      /*@                           */
   if branch then call BRANCH
   address TSO
 
   select
 
      when pfkey = "PF11" then,
         style = style//stylect + 1    /* next style                 */
 
      when pfkey = "PF10" then,
         style = (style+stylect-2)//stylect + 1       /* prev style  */
 
      otherwise nop
   end
 
return                                 /*@ BRDK_CHECK_STYLE          */