[ESRI software] In ArcView 3.x, a theme used to perform geocoding. A reference theme can be any point, line, or polygon theme that contains the necessary address fields. Each address component (such as street name, address range, street prefix, and street type) is stored as a separate field. The address fields can be contained in the reference theme itself or in a table joined to it. During geocoding, each address is matched to a feature in the reference theme that has matching address components (either the single address or address range), then coordinates for the new point features are determined.