Psalterium monasticum 1981 p 46 - edit: this comes out of nowhere, an adaptation of the A/ from H, as Mocquereau did, makes more sense.

Mocquereau/OMH + neumes from H, which has this A/ for Ascension with an alleluia at the end, and necessitated an adaptation by Mocquereau.

From 1916 LN draft / OMH

Compliant with OMH1922