OK, air forces. I'm going to work on the basis that 100 aircraft equals one full-strength air unit; in reality aircraft tended to be split up into much smaller detachments and spread out among the army units. Canada, which had exactly one aircraft in August 1914, would therefore in theory have an air unit with a strength of 001, except that I've not bothered to include it
For reference, I've also mentioned how many front-line aircraft each country had at the end of the war, and what they called their main units of organisation.
Also, I'd think that at the start of the war there's only one type of aircraft available, "Pre-War Scout", which has absolutely no attack factors at all - its only use is reconnaissance.
AUSTRIA-HUNGARY
"Luftfahrtruppen", strength=50
Austrian air units were known as D-Fliks (Divisions-fliegerkompagnien). About 500 aircraft at the end of the war.
BELGIUM
"Aviation Militaire Belge", strength=15
The Belgian air force was organised into escadrilles. 140 aircraft in 1918.
FRANCE
"1. Aviation Militaire", strength=100
"2. Aviation Militaire", strength=50
Escadrille. About 4,000 aircraft in 1918.
GERMANY
"1. Fliegertruppen", strength=100
"2. Fliegertruppen", strength=100
"Festungs-Fliegerabteilungen", strength=50
Abteilung, Staffel or Geschwader. 2,700 aircraft in 1918.
Germany also had 11 Zeppelins in August 1914, divided between the Army and Navy Airship Services.
ITALY
"1. Corpo Aeronautica", strength=100
"2. Corpo Aeronautica", strength=50
Squadriglia. 1,150 aircraft in 1918.
RUSSIA
"1. Imperial Air Service", strength=100
"2. Imperial Air Service", strength=100
Otryady. 550 aircraft in February 1917.
BRITAIN
"Royal Flying Corps", strength=50
"Royal Naval Air Service", strength=90
Squadron. About 2,600 aircraft in 1918.
UNITED STATES
"Aviation Section", strength=25
Squadron. 740 aircraft in 1918.