[otrs] Only allow customer user to submit ticket to certain category

Does OTRS have capability to only allow a customer user to submit ticket to certain category? If not, I am willing to write some code myself to make this happen. But would also like to hear your suggestions on this. This is what I have been thinking: 1. under admin interface, have check box available (list all categories) , when admin check certain boxes, some values will be written to customer table. 2. under customer interface, customer table will be looked upon to determine which categories will be displayed for customer to submit a ticket. Would like to hear your suggestion on: 1. which table to hold values of categories that a customer is allowed to submit his ticket to. 2. modules to changes etc.. Thanks. Alex