The Project Category attribute used the Idea and Project Category Parameterized Lookup. This is a parameterized lookup to display Idea Request Categories (Project Categories) based on the Idea Request Type (Project Type) selected. This lookup is dependent upon the mapping done in the Lookup Mapping Object.
The steps to create a new lookup mapping are below:
1. Go to Home - Lookup Mapping 2. Click on the 'New Lookup Mapping' button