Can we create Document Service taking DataArea for AIF ? Error:DataArea is SystemTable.

In visual studio i want to display all company names in drop down so that user can select and create transaction.

Yes i am able to fetch data of Standard tables which are part of service.

For example if i select Custservice in AIF->Services then i can create object of that service class and fetch custTable data.

But how can we fetch from System Tables for loading all company names,user names etc for which there is no service in AIF->Services

So i thought ceating new service i may able to do that but failed because while generating document service it’s throwing error as “DataArea is System Table.Generation is stopped”

What can i do ?