Re: 'Bevel' fraction

>  My question was how to make three different kinds of fraction. 
Yes, my question was whether you really needed to have access to
to the two inline versions at the same time (ie the second two examples
in your gif) in which case you _do_ need special markup or whether this
can be viewed as a stylistic aspect, and the renderer can just chose
itself whether to do inline fractions in the style of your example 2 or
your example 3.

Actually I suspect that trusting a machine to make such decisions will
not work and that you will end up needing special markup for it....