ISO 9849:2017 defines terms relating to geodetic field instruments only, e.g. distance meters, levels, theodolites and others, and their essential component parts which are normally used in terrestrial measuring operations of ordnance survey, topographic survey, plane survey and engineering survey. Therefore, terms concerning fields such as the following are not mentioned, for example, photogrammetry, astronomy, hydrographic survey and industrial metrology. Accessories which are not necessary for the functioning of the instruments are not dealt with. The terms are arranged in English alphabetical order.