I have a requirement to pass a variable in function module

in function module , i need to pass months

CALLFUNCTION'FIMA_DATE_CREATE'

       EXPORTING

         i_date                  = sy-datum

*       I_FLG_END_OF_MONTH      = ' '

*       I_YEARS                 = 0

     I_MONTHS                =  (  6 months )

*       I_DAYS                  = 0

*       I_CALENDAR_DAYS         = 0

*       I_SET_LAST_DAY_OF_MONTH = ' '

       IMPORTING

         e_date                  = lv_date

*       E_FLG_END_OF_MONTH      =

*       E_DAYS_OF_I_DATE        =

In I_months i need to export 6 months , how can i do that .

i tried lv_month = sy-datum - 6 , its not working .

can any one help me to do .

please

Thanks in advance