# Stepper motor holding torque without coils energized?

I want to know what torque a stepper motor can hold when stationary. They seem to only have one figure in specifications for holding torque which, I presume, is while coils are energised.

How is this normally handled in usage of stepper motors? Is there a way of calculating holding torque while coils are not energised? I know braking can be done by shorting the coils, but it's obviously not as effective as just holding one coil energised to maintain position. Is one coil usually just kept energised to hold position with maximum torque? Is there a limit to how long one coil can remain energised?