You ask for an object for the correct country, described using the iso 2-letter country code. you will need to supply information to the constructor. you may then call methods on that object to do whatever operations you need. conceptually each object represents a point on the ground, although you some grid systems may take that point to be a corner of a defined area. e.g. a 6-figure os national grid reference may be thought of as the point at the south-west of a 100m by 100m square.

this package also includes the extra module geography::nationalgrid::tw.