[css-text-4] change "Creates 1/4em extra spacing between" to "Creates extra spacing between"

[MurakamiShinyu]

https://drafts.csswg.org/css-text-4/#text-spacing-property

This proposal was found in the following issue:

• [css-text-4] Text-spacing is too strict #3229

1. In the above description of ideographic-alpha and ideographic-numeric, change "Creates 1/4em extra spacing between" to "Creates extra spacing between."

and this issue was resolved as:

RESOLVED: Add a new text-spacing:auto value, which is not the initial value.

I am ok with adding the auto value, but I think it's not sufficient. Changing "Creates 1/4em extra spacing between" to "Creates extra spacing between" is still necessary.

The "1/4em extra spacing" is not the best choice in many cases, and narrower space such as 1/6em is preferred. Apple iOS seems to use 1/6em for ideographic-alpha/numeric spacing.

For the auto value, UA can choose such better spacing value for ideographic-alpha/numeric spacing, but stylesheet authors cannot use the auto value when they need to choose specific text-spacing style, e.g., preference between allow-end and trim-end, or space-first and trim-start. So the spacing value of ideographic-alpha and ideographic-numeric should be same as the spacing value for ideographic-alpha/numeric spacing with auto.

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FYI, Vivliostyle supports the text-spacing property, with auto value which is equivalent to trim-start trim-end trim-adjacent ideograph-alpha ideograph-numeric and the ideograph-alpha and ideograph-numeric create 1/6em space. See https://docs.vivliostyle.org/#/supported-css-features#css-text-4

[xfq]

Indeed, different software (Adobe InDesign, Microsoft Word, Core Text, etc.) and different authors/publishers may have different preferences, and the point is that there is extra spacing between ideographs and non-ideographic letters/numerals. I feel like we can move "1/4em" to a non-normative note as a guideline to implementers who don't know how much space to add, instead of making it a hard and fast normative rule.

See also: w3c/jlreq#163

[xfq]

And since IIRC no browsers have implemented this property yet (except for IE, but IIRC the property names are different), I don't think we'll have any web compat issues.

[fantasai]

Accepting this under editor's discretion. @MurakamiShinyu @xfq Let me know if the edits look appropriate! Thanks!

[MurakamiShinyu]

@fantasai Yes, looks good to me. Thanks!

[xfq]

It looks good to me. Thank you, @fantasai!