Plan & doubts: sync between mdn/data and w3c/webref

[yarusome]

Update:

1. The utility is now available at yarusome/diff-webref-mdn.
2. I decided to update key by key first without introducing a major version bump.

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I'm finalizing a script to diff the CSS data in mdn/data and w3c/webref, and will make a series of PRs to sync the former with the latter where possible. The script will live in a new repository, and I'm learning how to deploy with (manual) GitHub Action so that any reviewers can get the diff by themselves.

I'm listing the details of the plan here, and would like to get some suggestions / approvements in advance to expedite the PR process.

PS: mdn/data#670 is related to, but can be separated from this plan.

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Format

No key contents will contain real sentences except for those used by the heads in "Formal definition", e.g. for "allElementsSVGContainerGraphicsAndGraphicsReferencingElements":

Before: "All elements. In SVG, it applies to container elements, graphics elements, and graphics referencing elements."
After: "all elements; in SVG, it applies to container elements, graphics elements, and graphics referencing elements"

This will avoid weird casings as on the font-family page and redundant periods as on the border-radius page.

[yarusome]

Preliminary analysis based on the diff

Bugs

For descriptors:

1. The computed and initial keys should be optional.
2. There shouldn't be the media and percentages keys. (Only the viewport-fit descriptor under @viewport has the percentage key, but its value is n/a.)

For properties:

1. The inherited key shouldn't be boolean as it's not guaranteed that the constituent properties of every shorthand properties have the same inheritance statuses.
2. The media key should be optional. (Most properties in Webref don't have this key.)

For selectors:

1. Functional notations shouldn't be stripped of parentheses as in ::cue/::cue() and :host/:host(). (Related issue: Regroup the page types for CSS selectors content#27526)

Enhancements

1. Consistently use n/a for keys explicitly marked so in Webref. This refers to the percentages key.
2. For shorthand properties:
   • add an array-valued shorthandFor key;
   • change the values of the keys that state "see individual properties" in Webref to "see individual properties" as well;
   • refactor {{CSSInfo}} accordingly.
3. For aliased legacy / compatible definitions:
   • add a string-valued "aliasFor" key;
   • remove any other keys;
   • remove the "Formal definition" section from corresponding MDN pages.
4. Change the appliesto key to appliesTo.
5. Allow most keys taking "see individual properties" as the value.

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I'm willing to spend time improving mdn/data and updating the macro, but I'm hesitant to do so since there's no clear signal from the MDN team, and my PRs on fixing/improving {{CSSXref}} (as well as several PRs from other contributors) have been left in the forgetted corners for quite some time :/