Angelus domini descendebat de caelo

Folio: 
156
Sequence: 
1
Office/Mass: 
E
Genre: 
A
Position: 
1
Cantus ID: 
001412
Mode: 
4
Differentia: 
ob
Differentia database: 
Manuscript Reading Full Text (standardized spelling): 
Angelus domini descendebat de caelo movebatur aqua et sanabatur unus
Manuscript Reading Full Text (MS spelling): 
Angelus domini descendebat de caelo movebatur aqua et sanabatur unus
Indexing notes: 
is this differentia a later addition?; what is in the upper left-hand corner?