When digital theodolite is fitted with electronic distance measuring units so that the distances and angles can be measured simultaneously they become total station these are operated using a multi-faction keyword which is connected to a microprocessor built into the instrument.
The total station is powered by small rechargeable batteries and built into its memory are a number of self-contained functions which include the measurement of the slope, distance, horizontal distance, vertical distance.
This is a data recording module which is also called as electronic field book. This data recording module record the data and additional information.