First: In time there is only one frame of reference.
Duration is measured with respect a moment in the past.
All observers are in the present. There is no observer in
the past or in the future who has a different measure.
Second: Speed affects clocks, not time.
A change in time is, for example, 10 seconds in the past or
10 seconds into the future. Clocks of the GPS are always in the present.
Third: The speed doesn't affect length.
The speed affects the perception of the relative observer.
