A stranding can be located geographically with the pair of coordinates latitude and length. However, the reference system and the coordinate system used should be indicated. Each country has an official coordinate system that differs from others according to certain parameters.

One of the concepts that defines a pair of coordinates is the Datum. It represents each one of the different (mathematically definable) models of body which adjusts the form of our planet. A geographic location will have different values of coordinates based on the adopted reference system.

Nowadays, the GPS offers by default the positioning in WGS-84, the “World Geodetic System” adopted by the constellation of satellites GPS. For Europe the ED-50 (European Datum 1950) is usually adopted.