(1) A ground control point established by a subsidiary survey (not a survey for establishing geodetic control), placed at or near an important cultural feature or other feature to be included in the final map, and identifiable on the photograph. The number of detail points selected will vary with the nature of the terrain and the amount of detail needed on the map. Ten detail points per photograph are usually sufficient. (2) A selected, identifiable point used, particularly in oblique photographs, to assist in correctly locating features displaced because of elevation.