Follows Calendar

Connects a holiday or festival to the calendar by which its date is reckoned, such as the Gregorian, Hebrew, Islamic Hijri or Hindu lunisolar calendar. It adds a durable, comparable entity identity for the existing calendar-system enum fact recorded on holiday entries; it does not replace that enum fact, which continues to classify every holiday exactly as before. The inverse reading, Calendar Followed By, names the same relationship from the calendar toward each holiday reckoned by it.