Function module

Hi frnds...

i have to pass say just 3 - 4 fields of a table from a function module. how do i declare it in the "tables" parameter.

eg. i have a itab with fields 'matnr', 'mbrsh','mtart' in the function module. how do i export it from the function module in the form of a table.

points assured for all answers...

regards,

Madan......