To be more precise (please see the enclosed P.D.F. file), I would like the same font possibilities in ConTeXt math mode as shown in the following table from Will Robertson's talk at 41 min 40 s for LaTeX unicode-math package:

In both LaTeX and ConTeXt, we have two kinds of fonts:

— a text font: multi-letter words;

— a math font: single letter words.

In math mode, using LaTeX, text fonts can use both

— text spacing: $\textit{abc ffi}$ gives abc ffi;

— math spacing: $\mathit{abc ffi}$ gives abcffi.

In math mode, using LaTeX, math fonts can use only math spacing: $abc ffi$ gives abcffi.

($abc ffi$ is equivalent to $\symit{abc ffi}$—\symxx commands were introduced in the 2015 update of the unicode-math package by Will Robertson, allowing upright, slanted, bold, etc. math fonts with \symup, \symsl \symbf, etc., respectively.)

However, in math mode, using ConTeXt, text fonts can use only TEXT spacing (no MATH spacing commands): $\text{\it abc ffi}$ gives abc ffi. So this is the FEATURE that needs to be added. I suggest that you implement a new set of commands called \textxx for this (text fonts with MATH spacing in math mode—please see the enclosed P.D.F. file).

As far as math fonts are concerned using ConTeXt in math mode, it's okay: $\it{abc ffi}$ gives abcffi. But you should note that in the source of ConTeXt you (Hans) introduced \mathit (and \mathup & \mathtf, \mathsl, \mathbf, etc.) as an equivalent of \it (\tf, \sl, \bf, etc., respectively) for "A.M.S. LaTeX compatibility", though in A.M.S. LaTeX the \mathxx commands are not MATH fonts but TEXT fonts with math spacing (as pointed out by Will Robertson in the very first seconds from 41 min 40 s of his talk in the link above) so it not compatible (but that's fine since the name \mathxx in A.M.S. LaTeX was not very well chosen in the first place but thereafter kept for backward compatibility, so that in ConTeXt we can keep it used for MATH fonts instead and introduce \textxx for TEXT fonts with math spacing, as suggested in the previous paragraph).

Please see the enclosed P.D.F. file that sums everything up to understand visually what I mean with the missing feature I request (adding new \textxx commands for text fonts with MATH spacing in math mode), and let me know what you think.

Maggyero