It cropped up quite a lot in
my Battle of Britain research, for example:
CX/JQ/93 para. 37
On 28/6 5 a/c of I./KG 76 (Fliegerkorps I) at NORA having engines changed. Date of delivery or armour-plating for them remains undetermined. (A)
CX/JQ/118 para. 17
Fliegerkorps I reported to Fliegerhorst Krefeld that KG 1 needed 100 sets of armour plates for He 111 machines and KG 76 needed 30 sets of armour for Do 17 Z machines. (A)