怎样获取字符串的后几位（rpgle）

D AEPROD          S              5    INZ('12345')                         
D AESUB           S              2    INZ(*BLANK)                          
C*                                                                         
C                   Z-ADD     *ZERO         WKLEN             2 0          
C     ' '           CHECKR    AEPROD        WKLEN                          
C                   SUB       1             WKLEN                          
C                   EVAL      AESUB=%SUBST(AEPROD:WKLEN:2)                 
C     AESUB         DSPLY                                                  
C*                                                                         
C                   SETON                                        LR        
C                   RETURN