How do you use *HIVAL and *LOVAL?????

Hello,
My Next assignment requires a generic search for customer's Last Name.

Would I use *HIVAL and *LOVAL, and it so, how do I incorporate it?

I have learned much from all of you in this form, and your help would be
greatly appreciated.
Thank You
Phil

     F*****************  FILE SPECIFICATIONS  ***********************
     F*
     F* Progam Name: R1002
     F* Author: Phil Hayes
     F* Completion Date: 11/7/99
     F*
     F* Purpose: Display customers based on search criteria of first two
     F*          letters of the last name.  User can then select the
     F*          customer in which they want to view the complete information
     F*          on in another display record.
     F*
     F*    DISPLAY AND SUBFILE RECORD FORMATS:
     F*
     F*              PROMPT: Initial Department Entry Screen
     F*              LOOKUP: Subfile to customers found
     F*              CTLOOK: Subfile Control Record
     F*              FOOTER: Text for command action keys
     F*
     F*
     F*
     F*
     F*
     F*
     FCSCSTPLFIF  E           K        DISK
     FC1002DSPCF  E                    WORKSTN
     F                                        RRN   KSFILE LOOKUP
     F*
     F*
      *
      *Arrays to store name values
      *
     E                    NAM         2  1
     E                    CNM         2  1
      *
     C***************  CALCULATION SPECIFICATIONS  ******************
      *
      *
     C                     MOVEL*BLANKS   HRANK  15
      *
     C           *IN03     DOUEQ*ON
      *
      *Display initial screen
      *
     C                     EXFMTPROMPT
     C                     MOVELNAME      NAM
     C           *IN03     IFEQ *ON
     C                     LEAVE
     C                     END
      *
      *
      *Clear the subfile
      *
     C                     MOVE *ON       *IN55
     C                     WRITECTLDEP
     C                     MOVE *OFF      *IN55
      *
      *Initialize Relative Record Number
      *
     C                     Z-ADD*ZERO     RRN     40
     C                     READ CSCSTPLF                 90
     C           *IN90     DOWEQ*OFF
     C                     MOVELCLNAME    CNM
      *
     C           NAM,1     IFEQ CNM,1
     C           NAM,2     ANDEQCNM,2
     C           NAM,2     OREQ *BLANK
     C                     ADD  1         RRN
     C                     END
      *
     C                     MOVELCLNAME    SLNAME
     C                     MOVELCFNAME    SFNAME
     C                     Z-ADDCUSTNO    SCUST
     C                     WRITELOOKUP
     C                     READECSCSTPLF                 90
     C                     END
     C                     ENDDO
      *
     C                     WRITEFOOTER
     C                     EXFMTCTLOOK
     C           *IN07     IFEQ *ON
     C                     EXSR DSPLAY
     C                     END
     C                     ENDDO
      *
     C                     MOVE *ON       *INLR
      *
      *
      ***************  SUBFILE LOAD ROUTINE  ************************
      *
     C           DSPLAY    BEGSR
     C                     READCLOOKUP                   95
      *
     C           *IN95     IFEQ *ON
     C                     LEAVE
     C                     END
      *
     C           SLNAME    CHAINCSCSTPLF             40
     C                     Z-ADDCUSTNO    DCUST
     C                     MOVELCLNAME    DLNAME
     C                     MOVELCFNAME    DFNAME
     C                     MOVELCSTRET    DSTRET
     C                     MOVELCCITY     DCITY
     C                     MOVELCSTATE    DSTATE
     C                     Z-ADDCZIP      DZIP
     C                     Z-ADDCPHONE    DPHONE
     C                     Z-ADDORDDAT    DORDAT
     C                     Z-ADDBALDUE    DBLDUE
     C                     EXFMTDSPLY
     C                     ENDSR