Download and save this:
TM-9-1985-9 German Explosive Ordnance
The list of abbriviations begins on page 537. Just about every imaginable German explosive projectile is listed along with its possible fuze combinations.
Sprgr. = Sprenggrenatte (high explosive or H.E. shell)
Z. = Zunder (German for fuze)
A.Z. = Aufschlag Zunder (percussion fuze)
Doop. Z. = Doppel Zunder (time and percussion fuze)
B.Z. = Bren Zunder (a time fuze that uses a slow buring ignition train that ca be adjusted to cause the shell to explode after a certain time of flight after it has been fired that is different from a mechanical time fuze or proximity fuze)
So, your A.Z. 23 is simply the number 23 percussion fuze for the 105mm H.E. shell for the Field Howitzer model 18M. And so it goes…