Breaking these down into manageable chunks ...

> ... we allow a construction in which 2 minutes since 2016-12-31 23:59:00 to 
> be 0 minutes since 2017-01-01 00:01:00 and for these to be UTC times, so that 
> the length of the 2 minutes is 121 seconds. Consequently, any coordinate we 
> defined through this kind of construction would be, in your words, a 
> non-metric time.

Yeah, I can see that would be "non-metric" -- but why in the world would we 
want to allow that? and in fact, how could you allow that???

CF time encoding involves *one* datetimestamp, not two. It would be a really 
bad idea to somehow mix and match TIA and UTC in one time variable -- specify 
the timestamp in UTC, but that processing tools should use TIA from there on??

two minutes is never, ever, anything but 120 seconds. Let's not confuse what I 
am calling a timestamp -- i.e.  the "label" for a point in time from a time 
duration. So:

the duration between:

2016-12-31 23:59:00 and 2017-01-01 00:01:00 

is 120 seconds in the UTC Calendar, and 121 seconds in the TIA calendar.

so:

120 seconds since 2016-12-31 23:59:00 will be a different timestamp if you use 
the TIA calendar than if you use the UTC calendar -- just as it maybe be 
different if you use any other calendar....

So what is the problem here?

Granted -- if you want to accurately create or use a tiem variable with the TIA 
calendar, you need a library that can do that -- but that is not CF's problem.













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