[Om] invisible times and invisible plus

[Jan Willem Knopper]

Paul Libbrecht wrote:
> Jan Willem,
> 
> I think a mixed-fraction symbol would be very useful and meaning-ful.
> But invisibletimes and invisibleplus really are not semantic-ful- 
> enough to my taste.
> 
> or?
I agree that a mixed-fraction is where there is a semantic difference,
and the other uses are not really important. 
A symbol a mixed-fraction would be good enough for my purpose.
> 
> paul
> 
> PS: in activemath we have internal symbols for mixed fractions, not  
> surprisingly.

I can do something with my own internal symbol, but I wanted to check if
there was a common way to do this.

> PPS: check MathML3, I vaguely remember it has a mixed-fraction concept  
> at the core... or at least it was discussed.

A fraction using invisibleplus is mentioned in presentation markup is
mentioned as an example of invisible operators (3.2.5.5. Invisible
Operators). But this is only about presentation.

I could not find it at some other place. But it might well be possible
that I missed it, or that it did not make it to the working draft (yet).

Thanks for the quick reply,

Jan Willem
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