§10.4 Register-referenced (dynamic) scaling.
for MULTIPLY: value = raw * ref / denominator
from field: int64 denominator = 3;
from field: moddef.v1.ScaleMode mode = 2;
the SF / factor register
from field: string point_id = 1;
from message moddef.v1.ScaleRef
§10.4 Register-referenced (dynamic) scaling.