The geocode is a numerical representaton of the collecting locality that can be read by machines and geographic information systems (GIS).
The most common format for the geocode in herbarium collections is a specification of latitude and longitude. This is most commonly expressed in terms of degrees, minutes, seconds and hemisphere, although decimal degrees and decimal minutes are sometimes used.
In addition to a locality and geocode, a precision or tolerance for the geocode calculation is sometimes included. This helps in assessing at what scale the locality record will be useful.
Geocodes can be derived from Global Positions Systems (GPS) in the field or from maps or gazetteers in the herbarium.
Sometimes the geocode is quoted as a grid reference, but this is seldom done correctly or completely and a more standard geocode needs to be recalculated.