Re: [csswg-drafts] [scroll-animations-1] Add predefined `@scroll-timeline` to spec (#6472)

Yeah, there's several examples. 

* CSS-wide keywords. We try not to expand this set much, and when we do keep them as generic words that are very unlikely to show up in other contexts so we can ban them from being used anywhere else without issue.
* Color spaces for `color()`. Here, the author-defined ones are segregated from CSS-defined by requiring them to be dashed-idents. We're *pretty sure* this list is gonna expand over time, and the most reasonable names to choose are *also* likely names for authors to choose, so keeping them clearly separate was important.
* Counters. Here we just allow the two namespaces to mingle, with author-provided ones overriding CSS-defined ones (except for a handful that we've banned from overriding, for perf or internal-consistency reasons). If I were doing this today I *might* take the `color()` approach and require dashed-idents, but the cultural concerns of minting *some* numbering systems as predefined names while others are dash-prefixed might have stayed my hand.
* Font-face names. The namespaces mingle, but predefined ones are non-overridable. We don't expand the set much, and when we have done so in the recent past we've used names that are very unlikely to collide with existing author-defined names (the `ui-*` names).
* probably a few more, i dunno off the top of my head

So we're all over the board in behavior, and I dunno where we wanna go with this. If we think we'll be adding to the list of predefineds over time, I suspect we want either "mingle, but authors can override names" or "authors must use dashed-idents", because it looks like the names we'd choose are halfway reasonable for authors to choose too. If we think the list will be pretty static, we can possibly go with "mingle, but predefineds are illegal to override".

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Received on Friday, 20 August 2021 17:03:49 UTC