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Re: [csswg-drafts] Versioning policy and backwards incompatible changes (#5114)

From: Tab Atkins Jr. via GitHub <sysbot+gh@w3.org>
Date: Tue, 26 May 2020 21:27:49 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-634288983-1590528468-sysbot+gh@w3.org>
> We also have a long term ambition to fully obsolete CSS2, which will then lead to the question as to where the normative definition of Level 2 will live.

I don't think we *will* have a normative definition of Level 2 at that point. It'll be obsoleted just as much as CSS 1 is.  We're not far from that point already.

> At the moment if we make a backwards incompatible change to Level 4, our practice is to make behaviour undefined/optional in L2 and L3 (and ignore L1),

I don't think that's our practice, either?

CSS2 had a lot of stuff declared undefined near the end of its process, not because of backwards-incompatible changes in the level 3 module, but because the behavior wasn't yet consistent between browsers and so we couldn't get 2+ passes for tests for any reasonable defined behavior.

Since then, I don't think we've gone back and undefined things because of a change in later versions, have we? We sometimes remove things because we prefer the levels to not *contradict* each other, just for confusion-avoidance reasons, but there's no sense in which an earlier level is a meaningful artifact which an implementor can decide to support vs a later level. They're just previous versions of the current document, is all.

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Received on Tuesday, 26 May 2020 21:27:50 UTC

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