raystuttgart
Civ4Col Modder
In the city screen in the list of goods is a line "Total = 0" below every good. What does that line display?
It just says that this city currently does not produce any of that Yield.

It is pretty clear once you actually produce some fo that Yield, because then you have the context.
(I am not sure if the text was changed in the recent text updates - maybe it was a bit clearer before.

The TXT_KEYs are those if you want to change them for yourself:
- TXT_KEY_YIELD_TOTAL
- TXT_KEY_YIELD_TOTAL_FLOAT