This Code Studio example provides an Event Action that will convert a location defined by Eastings and Northings to one defined by Latitude and Longitude.
As well as being a useful function, this Code shows how and Event Action can be used to take two Fields from a Record and to Update two other Fields in the same Record with derived values. For example, you may be importing data from a Legacy system that contains only Eastings and Northings data. If you set this Event Action to fire on Record Creation it will add the corresponding Latitude and Longitude co-ordinates. This will enable you to use the mapping power of Create.