DTV13 — Characterization of time offset as a role of duration is inconsistent

Clause 10.5 defines time offset to be a role of 'duration'. But the intent of time offset is to describe the difference between a local time and UTC time at a given instant. That difference is only a duration if we agree that there can be negative durations. Otherwise that difference must be described as a duration and a direction. The latter is what the introductory text describes.

Merge to Issue DTV13-101

The RTF agrees that 'time offset' is not just a role of duration – it is the characterization of a difference between a calendar and UTC that involves a direction (ahead of or behind UTC) and a duration. The verb that introduces the term – calendar1 differs from calendar2 by time offset – actually refers to a role of 'duration' but 'differs from' is an ambiguous wording. It is replaced by 'calendar1 is duration ahead of calendar2', with the same synonymous forms using + and -. 'time offset' then characterizes the difference as 'ahead' or the inverse 'behind' together with the duration.

Because Issue 13-101 moves the text in question, the revised text is included in the resolution of issue 13-101.