On Sat, 10 Sep 2016, Hans Åberg wrote:

>> On 10 Sep 2016, at 16:06, Hans Hagen <pragma@wxs.nl> wrote:
>> 
>> On 9/10/2016 12:57 PM, Hans Åberg wrote:
>
>>> The STIX fonts, and XITS then, support Unicode math semantic styles. So perhaps the TeX commands should expand to these:
>> 
>> what tex commands ... we're talking characters and they don't expand
>
> If one writes ASCII ${\bf x} {\bi x}$, it would expand to the expected Unicode $𝐱 𝒙$.

That is already the case.

Aditya