I've been looking at the Compline music attributed to 'Praenestinus' and wondering about the Te lucis ante terminum. This one sets the odd verses and uses a different tune from the 4 settings in LU, one similar to the mode vii tune in W. Douglas, whose 1st phase is identical to 'Palestrina's 2nd; my reconstruction is attached below.

A general question is where to look for a survey & index of Hymn tunes associated with the Office, and more particularly how different tunes get assigned to the rankings & seasons and how much variation there is by region & epoch. And of course it would be wonderful to be steered to a 16c Roman source!