Category Selector... help!

[KarenHall]

I'm trying to filter this layer so that when I select a project name, only the parcels specific to that project name are visible.

I've made it to the category action tab, but I'm lost on what a source field and target field are for.

I've attached a picture if that helps to clarify what I'm referring to.

[Neal_t_k]

Those are your matching fields, the fields you are basing your relationship on.  So for example you have two tables: ProjectName and Parcels  

ProjectName:

Name,  ParcelNumber

Pr1,  001

Pr1, 002

Pr2, 003

Pr2, 004

Parcel:

ParNum

001

002

003

004

So, the source field you would put "ParcelNumber" and in target you would put "ParNum"