Unable to find zener diode parameters

[ziggurat]

I have a problem with estimating the minimum and the maximum zener current of a specific diode. It's part number is "TZS4678" from these series.

I am thinking of finding I_{z max} this way:
I_{z max} = P_tot / V_{z max}

I'm not sure if I can find the maximum zener current this way. Also, I have no idea how can I find I_{z min}. Can you help me or give me clear instructions?

 

[Audioguru]

It might be a 1N4678 1.8V zener diode that has a detailed datasheet from Fairchild. Because its voltage rating is so low then its performance as a voltage regulator is poor compared to a 9.1V 1N(I forgot).
A zener diode's voltage is rated at its "tested current" which is only 50uA for the 1N4678. Its maximum current is 120mA but then its voltage will be much higher than 1.8V.