Going by other writing on that form, I think the top line reads "Officer Commanding 24 General Hospital" (at Etaples) followed by the following possibilities:
NYD: Not Yet Discharged or Not Yet Diagnosed.
I would tend towards "Not Yet Discharged" because the next entry shows a different venue than the General Hospital, but that line shows "Myalgia" which is obviously the diagnosis so maybe Not Yet Diagnosed is equally possible!
6 Con Depot is a Convalescent Depot which was at Etaples.
I found this piece of information on another website:
"Divisional rest stations began to be established in France in early 1915. Their purpose was to look after sick and lightly wounded. A man would usually stayed no more than about ten days at one before being returned to his unit.
Convalescent depots or camps looked after those who had been discharged from hospital but were not yet fully fit. The average stay was some 3 weeks. A man would then be sent to a base depot prior to being returned to his unit."
RRTB
