Customer exit variable using BADI (I_STEP = 3)

Hi Gurus,

I have question on using the 'Variable Validation' similar to how we use in CMOD report variable validation method. I have used the below to throw the error message in the variable entry screen if the user entry does not meet the condition specified in the code:

call function 'RRMS_MESSAGE_HANDLING'

             exporting

             i_class  = 'RSBBS'

             i_type   = 'E'

             i_number = '000'

i_msgv1 = 'XXXMessageXXX'(022).

             raise g_c_no_replacement.

Can someone explain how do I do this using the BADI method since the function module based exceptions would not work in BADI.

Thanks in Advance.

Regards,

_Mhel