Hi,
I want to display a list of fields in item master on a form of type II and want to store only those fields in ascii file which are checked by the user.

My requirement is something similar to the functionality of Easy SQL, where a user can select what fields he wants to hav in the SQL from the list of fields displayed.

Any idea how to do achieve this?

Use dynamic SQL. Refer to Baan documentation on how to write dynamic SQL and this board for some simple examples.