\RequirePackage{firamath-otf}

ks-new-engines.clo

 % Rolf Niepraschk, Rolf.Niepraschk@ptb.de
 
 \ProvidesFile{ks-new-engines.clo}%
-  [2020/09/14 v0.1f PTB `Kalibrierschein' new engines (RN/PTB)]
+  [2024/04/30 v0.1g PTB `Kalibrierschein' new engines (RN/PTB)]
 
 \RequirePackage[no-math]{fontspec}
 \setsansfont{texgyreheros}[
@@ -22,7 +22,10 @@
   Scale     = 1.05, 
   RawFeature={embolden=.5}
 ]
-  
+
+\RequirePackage[usefilenames]{firamath-otf}
+
+\iffalse  
 \RequirePackage{unicode-math} 
 \setmathfont{FiraMath-Regular.otf}[
 %\setmathfont{LatoMath.otf}[
@@ -31,17 +34,19 @@
   bold-style=TeX,
   Numbers={Lining,Proportional},
 ]
+\setoperatorfont\mathsf 
+\setmathfont{texgyreheros-regular.otf}[range=up/{Latin,Greek,num}]
+\setmathfont{texgyreheros-italic.otf}[range=it/{latin,greek}]
+\setmathfont{texgyreheros-bolditalic.otf}[range=bfit/{latin,greek}]
+\setmathfont{texgyreheros-bold.otf}[range=bfup/{latin,greek}]
+\fi
+
 \unimathsetup{%
   math-style = TeX,
   bold-style = TeX,
   mathrm     = sym,
   partial=upright              
 } 
-\setoperatorfont\mathsf 
-\setmathfont{texgyreheros-regular.otf}[range=up/{Latin,Greek,num}]
-\setmathfont{texgyreheros-italic.otf}[range=it/{latin,greek}]
-\setmathfont{texgyreheros-bolditalic.otf}[range=bfit/{latin,greek}]
-\setmathfont{texgyreheros-bold.otf}[range=bfup/{latin,greek}]
 
 \RequirePackage{newunicodechar}
 \newunicodechar{^^^^202f}{\,}% 'NARROW NO-BREAK SPACE' (\u202F, 8239)