[MotorBikeLes]

Mark, first your points about the Avo are correct. You effectively have a battery, resistor and meter in series (loads of resistance when on the high ohms range, otherwise the needle would wrap itself around the upper stop. It is only approx, but give a general answer "is this a low voltage zener?" your original question (except you did not mention low voltage). Please note that if you use the Avo on mid ohms range, or worse still on the low ohms range, not only do you not have the voltage to assess any zenering, but you may well have enough current flow to get all destructive. Back in my compact disc repair days, I used an AVO on the low ohms range to test sled motors etc. A very low reading usually meant faulty, whilst a middling reading also had the motor running happily.
The idea of a battery in series with a resistance (4K7 was mentioned) is providing a current limit and chance of meaningful reading. In this case the meter is reading volts across the diode.
Les.