Irish Transverse Mercator

The older Irish grid reference system required GPS measurements to be "translated" (using co-ordinate transformations).

While the existing UTM co-ordinate system partly fulfilled the requirement for direct GPS compatibility it had some drawbacks, including varying levels of distortion across the island due to the central meridian being at the west coast of Ireland.

An ITM co-ordinate is generally given as a pair of two six-digit numbers (excluding any digits behind a decimal point which may be used in very precise surveying).

With ITM it is possible to give a more accurate co-ordinate for a given location by using a decimal point after the initial six figure easting and northing.

The fact that the co-ordinate is in metres is indicated by the lowercase m. With ITM there is no provision for using myriad letters and truncated coordinates as there is with the Irish Grid.

ITM coordinates on an OSi map from 2006. In this example the easting and the northing are separated by a comma.
An illustration of ITM coordinates over a map of Ireland. Eastings are on the top/bottom. Northings are on the right/left.