a. Bearing: The horizontal angle made by the traverse leg with the magnetic north is called bearing.
b. Control point: The point whose co-ordinates are known is called control points.
c. Station: The known point where instrument is setup is called as station.
d. Horizontal angle: The angle made by two traverse leg in horizontal plane is called horizontal angle.
e. Zenithal angle: The angle made by the survey line to the zenithal line in vertical plane is called zenithal angle.
f. Traverse leg: Line joining between two stations is called as traverse leg.
g. Traverse Angle: Angle between two traverse legs is called as traverse angle.
h. Closing error: When first point of traverse doesn’t coincide with last point then an error appears, that error is called closing error. It is the distance by which the end of the traverse falls short of coinciding with the starting point. It is denoted by e and given by:
Closing error = √ (error in latitude) ² + (error in departure) ²
i. Angular Misclosure: It is the difference between sum of measured angles and the theoretical sum of the angles of a closed traverse. Also, the difference between the bearings of last line as observed from the first and last station in case of link traverse.
j. EDM: It stands for Electronic Distance Measurement. The instruments using EDM rely on propagation, reflection and subsequent reception of either light or radio waves.
The general principle of EDM comprises on sending a modulated electromagnetic beam from the master station by a transmitter to a reflector at the remote station where it is received by the receiver and returned back to the master station.