Re: [css-counter-styles] status of "additional" predefined counter styles

On Tue, Sep 9, 2014 at 1:36 AM, Jonathan Kew <jfkthame@gmail.com> wrote:

> In the current CSS Counter Styles draft,[1] we read that
>
> # These additional counter styles are not intended to be supported by
> # user-agents by default
>
> (in reference to the styles listed in the i18n WG's document.[2])
>
> However, test results[3] indicate that webkit and blink do actually
> implement a number of these as built-in counter styles; in particular, many
> of the Indian script/language names (with the exception of 'tamil'), and
> several more such as 'arabic-indic', 'persian', etc.
>

My understanding is that the phrase "not intended" indicates MAY, not a
requirement, prohibition, or recommendation. Therefore, I think UAs can
implement some or none of them as built-ins if they want. Anyway, I think
it makes sense to make the wording here more clear. In my opinion, it
should be either a SHOULD NOT, or a MAY.

A smaller number of the "additional" styles are also supported by Firefox,
> such as 'armenian', 'greek', and a number of CJK styles; and a handful also
> by IE.
>

The styles you listed supported by Firefox are actually parts of the spec.
They are not really "additional". Predefined Counter Styles includes all
the styles defined in the spec.


> Should such styles be moved to the standard collection of predefined
> styles within the Counter Styles spec, with the expectation that all
> browsers should support them? If so, we need to determine which ones to
> move. Or should browsers refrain from implementing these "additional"
> styles as built-ins, so that it's clear to authors that an explicit
> @counter-style rule is needed in order to use them? ISTM the current
> situation is unhelpful from an interop point of view.
>

I want to explain the current situation.

The landing of @counter-style support has actually broken some site
compatibility, and one of them is Wikipedia, which uses:

list-style-type: -moz-persian;
list-style-type: persian;

for compatibility. [1] Before @counter-style is implemented, the second
line will simply be ignored by Firefox as it does not include a defined
keyword. In the coming version, however, the "persian" in the second line
will be accepted as a custom identifier, and treated as an unknown counter
style which falls back to decimal. As a result, it shows decimal style
instead of persian.

I agree that authors can add @counter-style rules themselves, but I think
it should be allowed for UAs to improve the compatibility with each other.

Xidorn Quan

[1]
https://github.com/wikimedia/mediawiki-core/blob/a0c6a63e7f4231c864e56af6da5289467593065b/resources/src/mediawiki.legacy/shared.css#L942