The term TMA initially referred to Trimetrogon Aerial photography. In recent years, however, SCAR missions have been flown using several different camera systems. Since the term TMA was so well understood by the SCAR community, it was decided to keep TMA as part of the photographic identification. These relationships are expressed as connections between spatially touching lines, small areas contained within larger areas, lines that make up the sides of an area or polygon, etc. Topology does not provide information as to the features' meanings, only their identity and structural relationships as they define spatial objects.
Townships are an element of the United States and Canadian public-land survey systems.