About the liturgical calendar, you might consider using an existing list of occasions. I know the one used in Schneyer's 'Repertorium der lateinischen Sermones des Mittelalters', with a siglum for each occasion. I might have the list in digital format, if you are interested do get in touch in private email.
----- Mail original -----
De: "Paterson, Duncan" <[log in to unmask]>
À: [log in to unmask]
Envoyé: Jeudi 2 Novembre 2017 11:44:01
Objet: Re: Fixed and moveable dates in the Church calendar
I thought thats what @when-custorm was for. You would need to define church calendar so you end up with something along the lines of:
On 2. Nov 2017, at 10:28, Birnbaum, David J <[log in to unmask]<mailto:[log in to unmask]>> wrote:
I'm tagging information from medieval hymnographic manuscripts, where many of the texts are assigned to dates in the Church calendar, and I'd like to be able to search for records in the corpus by date. Some components of the services are tied to fixed calendar dates, e.g., "November 1", and I can tag those in a formalized manner with <date @when="--11-01">. But others are tied to moveable dates, e.g., "Second Sunday after Easter". I can describe those in prose, of course, but it would be easier to maintain consistency among the multiple taggers in the project if there were a concise formula for the moveable dates, comparable to the ISO date that we can use for fixed dates. I'd be grateful for suggestions or examples from similar TEI projects.