On 21 May 2014, at 4:46 am, William F Hammond <[log in to unmask]> wrote:

> So long as one minds the gaps in U+1Dxxx (actually the several gaps for which the unicode folk seem to have thought the characters were previously defined in the U+21xx block), though maybe it's not that much of an issue for \mathbf itself as opposed to \mathcal, \mathfrak, and \mathbb.
> 
> At least they were thoughtful enough to leave those slots empty.  :-)
> 
> Just seizing the opportunity to make everyone aware of the gaps.

Aye, this made the implementation far more messy than it could have been.
Unicode-math has quite a number of exceptions hard-coded with their own csnames, such as:

\usv_set:nnn {bb}{C}{"2102}
\usv_set:nnn {bb}{H}{"210D}
\usv_set:nnn {bb}{N}{"2115}
\usv_set:nnn {bb}{P}{"2119}
\usv_set:nnn {bb}{Q}{"211A}
\usv_set:nnn {bb}{R}{"211D}
\usv_set:nnn {bb}{Z}{ď2124}

The vargreek symbols in particular are in inconsistent locations, but thereís only a few of them so itís not the end of the world.

Cheers,
Will