Linking 2 or more subject areas in an OTBI report

Summary

We would like to build OTBI reports but will require to use 2 or more Subject Areas in some reports. What are the key fields to linking subject areas and are there doumentation of these key fields?

Content

Hi all,

We are working with OTBI and BI Answer to build reports that require data points from 2 or more subject areas.  We were recommended to use action link instead of just joining 2 subject areas directly, given the resulting report may not join the 2 subject areas properly.  We are having a difficult time identifying the key fields that can be used to link the 2 subject areas.  So, my questions is: