Overview of Managing Reference Data
Reference data is data that's associated with transactional objects, such as leads and opportunities. Reference data is organized into reference data sets.
The reference data model lets companies separate transactional data so that it can be used across business units (BUs) or only for specific BUs. A data set called the Common set is predefined with the application. You can use the Common set for reference data that you want to share across business units. You can also create and maintain company-defined sets and assign them to specific BUs.
Examples of reference data include lists of values, such as the Win/Loss Reason list of values in opportunities, opportunity sales methods lists, opportunity sales stages lists, and price lists.
All reference data is tagged with a configuration ID called Set ID. For example, every value in a list of values in an opportunity is tagged with a Set ID.
You can create separate sets and subsets for each business unit. Or, you can create more common sets or subsets to enable sharing reference data across several business units, without duplicating the reference data.

You assign reference data sets to set-enabled attributes in the Manage Business Unit Set Assignment page in Setup and Maintenance. To learn how you assign data sets to set-enabled data, see Specify Business Unit Set Assignments.