Regem apostolorum dominum

Folio: 
028v
Sequence: 
6
Office/Mass: 
M
Genre: 
I
Cantus ID: 
001125
Mode: 
6?
Differentia: 
?
Extra: 
001v
Indexing notes: 
Tone = 1--g-f-g--4; for ferial days when the Te Deum is said; is this Mode 2 transposed up a third, or is the clef misplaced?