ROOSOURCE

The table ROOSOURCE has information on the datasources. You can view this by issuing a SE16  (or SE11) and looking up ROOSOURCE. (I  am new to the world of SAP BI. I am posting my learning here.)

Typically, it holds the name of the Datasource, its type (attribute, text or hierarchy), the extract method, extract structure, etc.

Instead of me writing about something that I am not good at (yet ..), let me point you to a link that explains ROOSOURCE. Please see the explanation here.