On Tue, 26 May 2026 at 14:08, Dragan Škondrić via tz <[email protected]> wrote:
> Does the distinction between *canonical event identity* and *civil/time-zone > projection* seem technically meaningful from the perspective of people > who maintain or use TZDB? > I'm struggling to conceptualize what precisely you mean by "canonical event identity" that wouldn't already handled by a timestamp expressed either in UTC or in one of many specialized scientific timescales already in use. > A related question is whether there are existing terms, prior discussions, > or known models in the time-zone / civil-time community that already > address this separation between: > > 1. the identity of an event, > 2. the instant or time scale used for ordering, > 3. the local civil-time rendering, > 4. and the future replay of that event under changing time-zone or > calendar rules. > > It is unclear what your perceived distinction between (1) and (2) is. Do bear in mind that readers of this mailing list come from a wide array of disciplines, so we may not be well-versed in technical jargon outside our immediate remit of civil timekeeping. But for these broad purposes, where relativistic and quantum effects are negligible, events' timestamps are simply governed by their natural ordering to whatever precision is available or desired. So (1) and (2) are assuredly quite well-handled for civil purposes by UTC (and its predecessor timescales like UT/GMT), and (3) and (4) are handled by UTC in combination with TZDB. Our approach to calendar rules is to adopt the proleptic Gregorian calendar; see: https://data.iana.org/time-zones/data/theory.html#calendar Certain scientific applications, particularly pertaining to astronomy, may prefer other timescales like TAI or Terrestrial Time (TT), or even Julian day counts based on TT — along with leap-second corrections and updated ephemerides, these can be mapped onto UTC directly for the past and as approximations with diminishing accuracy into the far future. There are, of course, more advanced and specialized applications for which the effects of relativistic time dilation or quantum ordering are more significant. I would presume these would tend to have their own systems in place for grappling with the resulting timescales, as needs seem quite likely to vary significantly; I am not aware of any broadly-adopted framework that seeks to unify varying project-specific approaches. > The specification is archived on Zenodo: > > *KDS Calendar - Version 3.0* > DOI: *10.5281/zenodo.20067725* > > At this stage I am not asking for endorsement, adoption, or any change to > TZDB. I would simply appreciate any technical comments on whether this > framing is meaningful, already covered by existing practice, or > conceptually misplaced from the viewpoint of the TZDB community. > I glanced through the specification, and found that much of it hinges on calendar and timescale reform proposals that are firmly out-of-scope for TZDB's work and which I would expect would remain so even if adopted for a specific purpose within a scientific community; see: https://data.iana.org/time-zones/data/theory.html#planets I can't say for sure whether your proposed framing is "meaningful" or "misplaced" without better understanding the concrete shortcomings you feel existing practice may have. My sense, however, is that most potential concerns are already covered across a disparate array of sub-disciplines within the scientific community, albeit in domain-specific ways. In any case, depending on your goals, I suspect researchers within the relevant disciplines may be better positioned than we are here to evaluate your framing's utility, novelty, or completeness. -- Tim Parenti >
