On 1 May 2020, at 16:02, Wolfgang Schuster <wolfgang.schuster.lists@gmail.com> wrote:

Gerben Wierda schrieb am 01.05.2020 um 13:58:
\definetypeface [optima] [ss] [sans] [optima] [default]
\definetypeface [optima] [rm] [serif] [optima] [default]
\definetypeface [optima] [tt] [mono] [modern] [default]
\definetypeface [optima] [mm] [math] [optima] [default]
\setupbodyfont [optima]
As I now understand it, I have now defined the typescript for sans, but created a setup that sans is the fallback. I have also defined rm, tt and mm explicitly.

This does not work because you have no serif or math typescripts
for optima (\starttypescript [serif] [optima]) defined.

Yes, I was in doubt about that, but I guessed that the fallback maybe took care of that. 

   \setups[font:fallback:sans]

mm should be modern anyway, I think (not that I need it, I only want the ss form anyway).

G


Wolfgang