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[css3-fonts] ordinals value of font-variant-numeric (was: [CSSWG] Minutes Telecon 2013-08-28)

From: John Daggett <jdaggett@mozilla.com>
Date: Thu, 29 Aug 2013 22:26:17 -0700 (PDT)
To: fantasai <fantasai.lists@inkedblade.net>
Cc: www-style@w3.org
Message-ID: <164212801.5979814.1377840377194.JavaMail.zimbra@mozilla.com>

>From this week's CSS WG telcon:

> <fantasai> Missing http://lists.w3.org/Archives/Public/www-style/2013Jul/0170.html
>            from DoC
> fantasai: 'ordinals' to be with superscript/subscript values?
> jdaggett: Difference is that it doesn't have fallback behavior
> jdaggett: Since used for numerics, put it with font-variant-numeric
> fantasai: I think that logic makes sense, but,
> fantasai: as you pointed out superscripts and ordinals are often confused
>           with each other, so it would be helpful to authors to learn to
>           distinguish them if they are in the same property
> fantasai: also, it's the only value of font-variant-numeric that doesn't
>           actually affect digits
> jdaggett: Are you asking for the value to be moved?
> fantasai: Yes
> jdaggett: I disagree for reasons above
> fantasai: There are arguments on both sides here:
> fantasai: [summarizes arguments]
>   font-variant-numeric over font-variant-position
>     * doesn't have fallback behavior, so want to avoid font-variant-position
>     * related to typesetting numbers, so in font-variant-numeric
>   font-variant-position over font-variant-numeric
>     * doesn't affect numerals/digits, so weird to put in font-variant-numeric
>     * affects visual position/size just like superscript/subscript,
>       so makes sense in font-variant-position, despite lack of fallback

The 'ordinal' value of font-variant-numeric is used to allow the
substitution of ordinal forms within ordinal number.  So the text
"17th" would appear with the "th" portion displayed similar to how
superscripts are displayed.

I've included a visual example of ordinal variants in the latest draft
and added an example showing typical markup for these [1].

As John Hudson wrote earlier today [2], I think it would be a mistake
to group the 'ordinal' value with superscript/subscript variants
simply because they seem similar visually. Superscripts are semantic,
ordinal forms are not.  Superscripts can contain any content, ordinal
forms are limited to those forms needed to support ordinal number
display for a given script.

The 'font-variant-numeric' property is a loose grouping of features
generally associated with numeric formatting.  Besides 'ordinal',
other values typically only apply to digits in current fonts but
there's no such limitation in the underlying format.  I don't think
it's a stretch to imagine fonts that support simple fractions such as
'1/x' and 'n/2'.

The 'font-variant-position' property is currently a pair of mutually
exclusive values, 'sub' and 'super'.  For 'sub' and 'super' there is
fallback behavior defined but there is no fallback behavior for
'ordinal'.  Style settings for superscripts are generally only applied
to content included in the superscript.  The 'ordinal' value is
generally applied to an entire ordinal number but only the alphabetic
suffix will be affected.  See example in spec [2].

Although Microsoft included the ordinal feature with
superscript/subscript in their WPF API [3], design apps treat it
differently.  Within InDesign, the ordinal feature is listed next to
fractions rather than grouped with superscript/subscript [4].

On balance, I think we shuold leave the 'ordinal' value as part of
'font-variant-numeric'.

Regards,

John Daggett

[1] http://dev.w3.org/csswg/css-fonts/#ordinal-example
[2] http://lists.w3.org/Archives/Public/www-style/2013Aug/0657.html
[3] http://msdn.microsoft.com/en-us/library/system.windows.fontvariants.aspx
[4] http://media.kelbymediagroup.com/layersmagazine/images/tutorials/design/indesign/18/image8.jpg

Further background on ordinals and the ordinal feature in OpenType:

John Hudson's explanation of ordinals:
http://lists.w3.org/Archives/Public/www-style/2013Jul/0198.html

Thomas Phinney on OpenType ordinal forms:
http://blogs.adobe.com/typblography/2006/07/confused_by_a_a.html

Typophile thread on ordinal numbers in various languages:
http://typophile.com/node/42577
Received on Friday, 30 August 2013 05:26:44 UTC

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