\font\SILmfont={[/usr/local/texlive/2024/texmf-dist/fonts/opentype/public/fira/FiraSans-SemiBold.otf]:+clig;+liga;+tlig;+ss04}\SILmfont
\def\SILmfontname{Fira Sans SemiBold; Stylistic Set 4}%