Data files can be created by Ctrl-N) - the file creation wizard will guide you through the process. It is possible to have more data files, although (in my opinion) vast majority of users will come along with just one file containing their parish.→ (
More files can mean more confusion. It is recommended to have just one main file, that will be always opened on application start. Unless you move the data file, you can forget that you have some data file - it is opened, saved automatically.
This file holds all data needed for run of program. Backup this file regularly and you are on safe side.
Data file from the versions preceding 18.104.22.168. It is just named differently, but that is only difference to regular data files.