Answer:
In PeopleSoft we have mainly 2 types of primary buckets for tables: Control tables and transaction tables. Control tables store information related to the org structure of the company and all business rules. Transaction tables store data of employees for daily ongoing business activities. Control tables are mostly driven by SETID. SETID is a high level key that is used to identify a group of rows called table set. SETID is tied to a business unit which is an organizational entity that can maintain its own transaction data. So through the use of SETID, we can expose data from one business unit to the other or keep it restricted to the business unit as applicable. In order to do this, all the control tables are divided into record groups. So when a business unit is created, a row is entered in table set control component for that business unit and for each record group, the SETID for the business unit is defaulted. This is called table set sharing. Based on this setup, when a user goes to transaction page like job data and tries to lookup control table related fields like job or department, user will see those values which are tied to the SETID that users BU is tied to in the table set control setup.