USER_COMMAND logic

I have below code

{MODULE user_command_0100 INPUT.

DATA : ok_code LIKE sy-ucomm,

save_ok LIKE ok_code,

output LIKE ok_code.

ok_code = sy-ucomm.

save_ok = ok_code.

CLEAR ok_code.

CASE save_ok.

WHEN '&F03' OR '&F15' OR '&F12'.

LEAVE PROGRAM.

WHEN 'DISPLAY'.

LEAVE TO SCREEN 100.

WHEN OTHERS.

output = save_ok.

ENDCASE.

ENDMODULE. " USER_COMMAND_0100 INPUT}

In the above code I want to also add command for following functions

1) find 2) print 3) First Page 4) Next page 5) last page

what is the code to be written for these functions? is there a list of these functions like I have written for 'LEAVE PROGRAM'.

Regards,

Santosh