Extend the General Roman Calendar with National or Diocesan data

The General Roman Calendar can be extended so as to create a National or Diocesan calendar. Diocesan calendars depend on National calendars, so the National calendar must first be created. The first step in creating a national or diocesan calendar, is to translate the data for the General Roman Calendar into the language for that nation or diocese. (see Translations) A national calendar may have some festivities in common with other national calendars, for example the patron of a wider region. In this case, the festivities for the wider region should be defined separately, and the languages applicable to the wider region should be set; the wider region data will then be applied automatically to national calendars belonging to the wider region.