The localisation files are .csv files (Comma Seperated Values files) that can be found in the localisation folder. These files serve to provide the text that a player will read for a given internal ID. The display text will also change depending on what language has been selected.
All localisation files are in the same format of this:
Ignoring the sharp sign, a line begins with an internal text ID. Then each language will have its own text to display. For example:
Instead of displaying d_cornwall whenever the Duchy of Cornwall is being refered to, the game will replace it depending on what language has been selected as the user's language. So if the user has selected English, then the text Cornwall will be displayed. Alternatively, if Spanish has been selected, then Cornualles will be displayed.