This is a system list. The choices are "Revised Funding" and "Original Funding" (the default). This is a notational field that can be used to separate funding request amounts on reports.
If you select "Portfolio" (the default) you can select any program and project in the table.
If you select "Program" a dropdown list appears and you are required to select a program. All lines that you add to the table will be locked at that program and you will only be able to select projects within it.
If you select "Project" a dropdown list appears and you are required to select a project. All lines that you add to the table will be locked at that project.