Instruments used for triangulation and trilateration

(1) A micrometer theodolite of an approved pattern reading directly to one second of arc, or better, shall be used for tertiary Land Surveyors 19 (2) A micrometer theodolite of an approved pattern reading directly to twenty seconds of arc, or better, shall be used for (3) Electronic distance measuring equipment of an approved pattern shall be used for trilateration distance measurement.