A more thorough explanation:

Definition: An ebdomadarius is an officer in a cathedral church who is responsible for overseeing the regular performance of divine service and assigning duties to choir members. The term comes from the Latin word "ebdomada," which means "weekly."

One example of an ebdomadarius's duties might be to ensure that the choir is properly rehearsed and ready to perform each week's music for the Sunday service. They might also be responsible for scheduling the choir's practices and assigning specific parts to each member.

Another example of an ebdomadarius's responsibilities might be to oversee the use of liturgical texts and ensure that they are being used correctly during services. This could involve working with the choir and other church officials to select appropriate hymns and readings for each week's service.

Overall, the role of an ebdomadarius is to ensure that the cathedral's divine services are performed with the highest level of excellence and reverence possible. They play a crucial role in maintaining the spiritual life of the church and ensuring that its members are able to worship in a meaningful and fulfilling way.