table for authorisation values

Hi,

I have one requirement to fetch the plants for which user is authorised.

In user profile authorisation data, authorisation for plant is given at organisational level. I need to fetch the plant value from organisational level and comapre it with the value in z table. If the value does not match, system should display message " no authorisation for given plant".

My question is that where are these authorisation values stored? Do we have any BAPI or FM to fetch these values? I have only userID as input and WERKS as field. I believe that in authorisation data, no authorisation object is available at organisational level.

Request your help.

Thanks.