Approximate values in DeviceOrientation

Should implementations attempt to calculate values that are not
determined by hardware devices?

For example, given I have a device that can give me alpha, beta, and
gamma instantaneous values, but can not determine rotation rate by
itself.  Should we be monitoring these values and producing
RotationRate?  I tend to think we shouldn't get in the way here and
not hardcode any calculations into the ua directly and, instead, we
should just provide the values and let script have the raw values.

Doug Turner