This Peoplesoft HCM tutorial explains Business Unit, SetID, TableSet.
Peoplesoft HCM Business Unit, SetID, TableSet
If you look at the Table fields through Query Manager, you will find many Peoplesoft Tables contain SetID field. Tables that have SetID field include Location, Jobcode, Department, Salary Admin Plan, Employee Class, etc.
SetID is a grouping for Business Unit in order to restrict or grant access to data within a table. If SetID contains only one Business Unit, the SetID is called Physical SetID. If more than one Business Unit, it is called Logical SetID.
When you create a Business Unit, you can assign a default SetID.
By creating different SetID, when an employee from U.S. Business Unit selects a location from Prompt Box, only the U.S. locations are available for selection. When an employee of U.K. Business Unit selects location, only U.K. locations are available. It is also possible to create another SetID so that both U.S. and U.K. employees can choose all locations.
According to official definition:
An operational subset of an organization. Business units can be independent legal entities, or organizations that need to segregate their financial data for accounting purposes, or operational centers that segregate their operations for management purposes.
Simply put, it is up to the company to define Business Unit.
You can also select SetID for Business Unit in TableSet Control
Tablesets are rows of data in different Tables of the same SetID.
In the below example, each color is a TableSet.
Setup sequence of foundation tables in the implementation
2) TableSet ID
3) Business Unit
4) TableSet Control
5) Business Unit Options Default
6) Location Code