What does "4 below 12000" mean in regard to a transformer primary?

[Calrissian45]

I've asked a customer for the nominal voltage on their distribution system and all they'll tell me is to specify a transformer that is "4 below 12000." I haven't heard this jargon before so I'm not sure if he's referring to 4 taps below 12 kV or 4% below 12 kV (i.e., 11,520 V).

 

[Hv&Lv]

Generally speaking, it’s taps of 2.5% each, so the taps would be:
+5%
+2.5%
0% 12,000
-2.5%
-5%
-7.5%
-10%

 

[Calrissian45]

Thanks for the explanation. That helps a lot.