[css-text] text-transform note on "casing" is inaccurate

[cookiecrook]

• Note immediately following this text-transform Example 3 https://drafts.csswg.org/css-text/#example-5b7dad2f

NOTE: The purpose of text-transform is to allow for presentational casing transformations without affecting the semantics of the document. Note in particular that text-transform casing operations are lossy, and can distort the meaning of a text. While accessibility interfaces may wish to convey the apparent casing of the rendered text to the user, the transformed text cannot be relied on to accurately represent the underlying meaning of the document.

The last sentence makes it seem like all accessibility APIs are concerned with is the casing, which is not true. Assistive Technologies (AT) convey any number of font and rendering characteristics, including the spacing of text-transform: full-width; (conveyed by HoverText on Mac/iPad and presumably ZoomText on Windows). Of note: there are downstream bugs wrt to some ATs or speech engines, but exposing the wrong data to the API is not a good solution.

I believe all parties acknowledge full-size-kana is problematic to convey due to its resulting change in meaning of the text as outlined in Example 5.

I'd propose the following replacement for the note:

NOTE: The purpose of text-transform is to allow for presentational casing and layout transformations. Note in particular that text-transform: full-size-kana; casing operations are lossy, and can distort the meaning of a text. While the transformed text cannot always be relied on to accurately represent the underlying meaning of the document, accessibility interfaces may still need to convey the rendered text to the user to accurately present speech, braille, or re-rendered text characteristics, including case and spacing.

[fantasai]

Most case transforms are lossy though, not just full-size-kana. Even uppercase is lossy, as in some contexts casing is significant; and in others we drop information for the case transform (e.g. Greek drops accent marks when uppercasing).

[cookiecrook]

How about this:

NOTE: The purpose of text-transform is to allow for presentational casing and layout transformations. Note that casing mutations are lossy, and can distort the meaning of a text. While the transformed text cannot always be relied on to accurately represent the underlying meaning of the document, accessibility interfaces may still need to convey the rendered text to the user to accurately present speech, braille, or re-rendered text characteristics, including case and spacing.

And maybe a separate note about full-size-kana output expectations?