WW1 logbook query

In a WW1 logbook I have been loaned, what do the abbreviations W.O.P, C.O.P, and E.O.P stand for?

It belonged to John C B Firth, an 11 kill Camel pilot of 45 Sqn. Some lovely comments, such as

“05/3/18..6423….1-10…..EOP……Nothing doing. “Lizard walking round inside of engine!”
“10/3/18..6423….1-40…..EOP……Sat in sun over Treviso. No E.A. Came in d–d cold, nearly frostbitten”
and
“27/3/18..6423….2-15…..EOP……Scrap with 10 DIIIs. Williams 1 in flames, Thompson and self 1 OOC (out of control).Guns jambed as usual.”

He was flying Camels from Istrana on the Italian front at that time, and ceased operational flying on 28/3/1918 with a total of 420hrs 35 mins flying hours, 394hrs 15 mins of which were noted as “War Flying”.

He then appears to have continued instructing, on Camels and Avros at Beaulieu, then Gosport and CFS Upavon, ending on 1/2/1919 with final total of 646 hours.

Fascinating document.