Re: Ada.Calendar.Formatting.Image (or Time_Of) changing the time

[Optikos <ZUERCHER_Andreas@outlook.com>]

On Thursday, March 5, 2020 at 5:29:35 PM UTC-6, Randy Brukardt wrote:
> Optikos wrote in message 
> news:f94395b7-f2de-4c49-8edd-b24bfa64cc37@googlegroups.com...
> >On Tuesday, March 3, 2020 at 5:49:35 PM UTC-6, Randy Brukardt wrote:
> >> "Simon Wright" wrote in message
> >> news:lyv9nl8p6w.fsf@pushface.org...
> >> ...
> >> > There was a conversation on Ada-Comment in June last year, in which it
> >> > turned out that compiler implementers may have have been 
> >> > misinterpreting
> >> > the ARM. It was quite confusing.
> >>
> >> Not just a conversation, but also a Binding Interpretation AI (which
> >> therefore applies to Ada 2012 compilers), AI12-0336-1.
> >
> >Shouldn't these Binding AIs that take effect from a past edition of the ISO
> >standard onward (and not merely incorporated into Ada 2020 or Ada
> >202X post-2020) ..be an ISO/IEC corrigendum..?  Allowing errata be
> >permanently published semi-officially in any forum other than
> >cummulatively in an official ISO/IEC corrigendum seems to be against the
> >ISO/IEC rules.
> 
> Not necessarily. ISO has very strict limits on the number of Corrigenda that 
> can be issued for a particular standard; after that the only choice is to 
> update the Standard.
> 
> Remember that from ISO's perspective older standards don't actually exist;

Well, there are a few finer points, for the interested reader.  Remember that so-called Ada 2005 (officially ISO/IEC8652:1995/Amd1:2007) was merely an amendment is ISO/IEC-speak.  If so-called Ada2020 is fashioned likewise as an amendment ISO/IEC8652:2012/Amd1:2020 (or :2021, instead of a new edition as Ada 2012 was as officially ISO/IEC8652:2012), then all the Binding AIs that are retroactive back to Ada 2012 would need an official ISO/IEC corrigendum no later than the official release date of Ada 2020's ISO/IEC standard document.  But if Ada 2020 is released instead as a new edition (say, ISO/IEC8652:2020 or ISO/IEC8652:2021), then this new edition would eclipse the older ISO/IEC8652:2012 as you describe and no harm no foul to a not-corrigendumed ISO/IEC8652:2012 that got left in history because by the corrigendum's due-date it became a moot point due to :2012 no longer being the standard in effect.
 
> only the latest version is relevant to ISO. So the difference between 
> non-Corrigendum Binding Interpretations and Amendments is non-existent to 
> ISO.

Because ISO/IEC amendments, corrigendum, technical reports, and standards are well-regulated published documents, that sentence needs to be reworded to be correct:  So the difference between
1) non-Corrigendum Binding-Interpretation AIs outside of ISO/IEC officially-published documents
and
2) any other recorded vote by the ARG on matters pursuant to the culmination in a forthcoming ISO/IEC document
is non-existent to ISO.

My point is that if Ada 2020's ISO/IEC is officially emitted the way that so-called Ada 2005's official amendment ISO/IEC8652:1995/Amd1:2007 to official standard ISO/IEC8652:1995 still in effect, then these binding AIs need to be pursuant to not only an ISO/IEC8652:2012/Amd1:2020 (or :2021) but also an ISO/IEC8652:2012/Corr1:2020 (or 2021) to be retroactive back to 2012.  Hence, it would be advantageous in this regard for the Ada 2005 model of mere official amendment to a still-in-effect prior standard to be avoided and the Ada 2012 model to be enacted for Ada 2020.

> But as a practical matter, people continue to use older standards and they 
> need corrections (not allowing implementers to fix language bugs would be 
> worse; why would anyone want to implement nonsense?). Such users need 
> guidance as well, as do the implementers.
> 
> For ACATS purposes (which maintains testing all of the older standards 
> except Ada 83), generally non-Corrigendum binding interpretations are 
> optional for older standards, which means that either the original wording 
> or the new wording is allowed. (We prefer the new wording, of course, but 
> there's no mechanism to require it.) OTOH, Amendments are ignored for the 
> purposes of testing older standards -- that's why we classify them 
> differently.

But conversely unlike amendments, a corrigendum ISO/IEC8652:2012/Corr1:202X to ISO/IEC8652:2012 is normative retroactively to 2012 until ISO/IEC8652:2012 is supplanted by an ISO/IEC8652:202Y even if X and Y are different, say, for Ada 2029 being the next official edition of the standard ISO/IEC8652:2029 where Ada 2020 ended up (unwisely in my opinion) being a mere amendment ISO/IEC8652:2012/Amd1:2020 (or :2021) analogous to Ada 2005 being a mere amendment ISO/IEC8652:1995/Amd1:2007.  This retroactive correction via a corrigendum matches this thread's intended normativeness of Binding AIs, whereas ISO/IEC's amendment term-of-art does not, avoiding general-purpose dictionary definitions of amendment, which might also have crept into this thread.