RE: [css3-writing-modes] text-combine-horizontal and half-width numerals

[fantasai:]
> Sent: Wednesday, February 20, 2013 6:09 PM
> To: www-style@w3.org
> Subject: Re: [css3-writing-modes] text-combine-horizontal and half-width
> numerals
> 
> On 02/20/2013 05:49 PM, Sylvain Galineau wrote:
> > When combining two digits into a 1em box, using half-width numerals
> seems preferred.
> > If the current font family does not have glyphs for half-width digits,
> > should the UA fall back to the next family in the list?
> 
> No, it should just place them (if they seem to fit: in most proportional
> fonts they do) or scale them.
> 
Can you elaborate on why you think this is preferable?