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The TimepointRelativeTarget defines the planned time between the two activities, expressed as an a non-negative ISO 8601 duration.
The TimepointPreWindow describes the amount of time, expressed as an a non-negative ISO 8601 duration, to which the relative time between the two activities may be shortened with respect to the value in TimepointRelativeTarget.
The TimepointPostWindow describes the amount of time, expressed as an a non-negative ISO 8601 duration, to which the relative time between the two activities may be elongated with respect to the value in TimepointRelativeTarget.