Hi,
In the range you describe the program does apply a mash temperature correction factor (actually in advanced options) to estimate the FG. Outside that range the factor is not applied, and FG is estimated from just the average yeast attenuation.
The reason for the limited range is simple. I only had a limited amount of FG data for the mash correction, and once we get too low or too high, the alpha/beta enzymes are not as active, so the mash correction factor is not accurate. Also when we get too low or too high, we're probably not in a mash conversion step in any case. So I had to set some reasonable limit to identify the conversion step (particularly for multi-step mashes) so I went with the range that most people use for conversion of sugars (and also the range I had experimental data for).
Brad
