\enabletrackers[colors.define]

% \nopdfcompression

% \setupcolors[rgb=no, cmyk=no]
% \setupcolors[rgb=yes,cmyk=yes]
% \setupcolors[rgb=yes,cmyk=no]
% \setupcolors[rgb=no, cmyk=yes]

\definecolor[PantoneOneEightSeven][r=.9,e=Pantone 187 U]

\definespotcolor[dtkred]     [PantoneOneEightSeven][p=1.0]
\definespotcolor[dtkredlight][PantoneOneEightSeven][p=0.6]

\starttext

dark: \blackrule[width=4cm,height=4cm,color=dtkred]

light: \blackrule[width=4cm,height=4cm,color=dtkredlight]

check: \blackrule[width=4cm,height=4cm,color=PantoneOneEightSeven]

\stoptext

