Going from a pdf file i found a link to on the foma website regarding Foma Action 400, which if im not mistaken is the only emulsion recipe they use for 400 iso film..

The pdf file puts forth that foma action 400 emulsion can be shot any where from 200 iso to 800 iso, and be properly developed by using the stock 400 iso time/developer combinations.

With the time, and religious idolatry put forth into making development tables for different iso of each film... the question i have is, if the foma literature is accurate why has anyone bothered to do the alternate developing times