- From: Chris Lilley via GitHub <sysbot+gh@w3.org>
- Date: Tue, 12 Oct 2021 12:24:13 +0000
- To: public-css-archive@w3.org
Regarding optionality and the default: CSS Fonts 4 does not specify that kerning is on by default. The initial value is 'auto':
> auto
Specifies that kerning is applied at the discretion of the user agent
> When set to auto, user agents can determine whether to apply kerning or not based on a number of factors: text size, script, or other factors that influence text processing speed.
However it does claim that:
> When rendering with OpenType fonts, the [OPENTYPE] specification suggests that kerning be enabled by default.
I don't find that suggestion in [the definition of the kern table](https://docs.microsoft.com/en-us/typography/opentype/spec/kern) or [the GPOS table](https://docs.microsoft.com/en-us/typography/opentype/spec/gpos) and find the opposite in the [OpenType overview](https://docs.microsoft.com/en-us/typography/opentype/spec/overview):
> Many features expose _optional capabilities_ that authors and typographers may choose to use at their discretion; for example, small cap forms, or **kerning**.
So I wonder where that claim came from and whether we should remove it.
Regarding the specifics of kerning and CJK, I wonder if we can expand the mention of "script" quoted above to give the specific details that fixed-width glyphs should not be kerned. I don't find the 'palt' or 'vpal' tables in [the OpenType specification](https://docs.microsoft.com/en-us/typography/opentype/spec/), nor in the [TrueType specification](https://developer.apple.com/fonts/TrueType-Reference-Manual/). Where are they defined?
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Received on Tuesday, 12 October 2021 12:24:15 UTC