This is a heuristic, not a published formula. 1.2 points/°C (≈0.67 points/°F)
reproduces the commonly cited "mash at 149 °F for a dry beer, 156 °F for a
full one" rule of thumb. It's applied whenever the engine can read a mash
temperature from the recipe, and clamped by
MASH_TEMP_ATTENUATION_MAX_SHIFT.
Attenuation shift per °C away from MASH_TEMP_ATTENUATION_REFERENCE_C, in percentage points, cooler mashes attenuating more.
This is a heuristic, not a published formula. 1.2 points/°C (≈0.67 points/°F) reproduces the commonly cited "mash at 149 °F for a dry beer, 156 °F for a full one" rule of thumb. It's applied whenever the engine can read a mash temperature from the recipe, and clamped by MASH_TEMP_ATTENUATION_MAX_SHIFT.