x = 'alphaBETA'                                  /*define a string to a REXX variable.  */
y = upper(x)                                     /*uppercase  X  and  store it ───►  Y  */
z = lower(x)                                     /*lowercase  X   "     "    " ───►  Z  */

         /*Some REXXes don't support the  UPPER  and  LOWER  BIFs  (built-in functions).*/