The instrument station is entered on a header line, followed by several lines each defining a target station and the observations to it. This is used for horizontal angle data and multistation GPS data. It can also be used as an alternative to the line observation format for terrestrial data types such as distances and azimuths. The format is:
inst_stn_definition trgt_stn_definition observation observation trgt_stn_definition observation observation trgt_stn_definition observation observation inst_stn_definition trgt_stn_definition observation observation trgt_stn_definition observation observation ....For grouped point observations (for example correlated sets of point coordinates), the instrument station definition is omitted, and the end of the group is indicated by an #end_set command, that is:
stn_definition observation observation stn_definition observation observation stn_definition observation observation #end_set stn_definition observation observation stn_definition observation observation #end_set ....
The station definitions inst_stn_definition and trgt_stn_definition (instrument station definition and target station definition) define the station code (the station code from the coordinate file) and the height of the equipment above the station. The preceding #data command may specify that the height is to be omitted (with the no_heights option), in which case the height is treated as being zero.
Each observation definition (observation in the formats above) includes the value of the observation (e.g. the length for a distance measurement). It may also include the error of the observation, and additional information such as refraction coefficient codes, observation classifications, and so on. There may be more than one observation type on each line. For example a data block may hold readings from a total station which include horizontal angle, zenith distance, and slope distance. The contents of the observation section is defined in the preceding #data command.