Mary Mother of the Church (1)
This new compulsory memoria is to be observed on the Monday after Whit Sunday. The fact that the Decree establishing it has emerged from the CDW and not from Ecclesia Dei makes clear that it applies to the Ordinary and not at all to the Extraordinary Form. This is confirmed beyond any doubt by the phraseology of the Decree and the details of the Propers issued.
Whit Monday, Monday in the Octave