Superscript and Subscript Characters in General Use

[Khaled Hosny]

On Thu, Jan 12, 2017 at 12:24:29PM +0900, Martin J. Dürst wrote:
> On 2017/01/11 17:32, Richard Wordingham wrote:
> 
> > The truly straight Unicode approach in HTML is to use 19⁄45.
> > Just entering those 5 characters into a text entry box in Firefox gave
> > me a properly formatted vulgar fraction.  That is how vulgar fractions
> > are supposed to work.  Unfortunately, one may need to avoid 'exciting
> > new fonts' in favour of those with a large, working repertoire.
> 
> Just for the record: The vulgar fraction display also happened in
> Thunderbird (on Windows). Firefox and Thunderbird use the same display
> engine. I have switched HTML display off, because I prefer to read all my
> mail in plain text, but it still worked.

This is done by HarfBuzz which automatically activates OpenType
frac/dnom/numr features for <digits><fraction slash><digits> sequences,
so if the font has the features one gets vulgar fractions out of box.
This works in Chrome as well since it uses HarfBuzz (older version of
Chrome didn’t enable HarfBuzz by default for Latin so the fractions
might not show there).

Regards,
Khaled