In strc-flt.mkvi \c!suffixstopper is undefined

\unexpanded\def\thecurrentfloatnumbersuffix
{\doifsomething{\floatcaptionparameter\c!suffix}
     {\floatcaptionparameter\c!suffixseparator
      \floatcaptionparameter\c!suffix
      \floatcaptionparameter\c!suffixstopper}}

Perhaps it need to be added to \setupcaptions ?

\setupcaptions
[\c!location=\v!bottom,
   \c!grid=,
   \c!before=, % not used (yet)
   \c!inbetween={\blank[\v!medium]},
   \c!after=, % not used (yet)
   \c!spacebefore=,
   \c!spaceinbetween=, % replaces fuzzy inbetween dual usage
   \c!spaceafter=,
   \c!width=\v!fit,
   \c!minwidth=\v!fit, % id est: the width of the floatbox in some cases
   \c!headstyle=\v!bold,
   \c!headcolor=,
   \c!leftmargin=\zeropoint,
   \c!rightmargin=\zeropoint,
   \c!outermargin=\zeropoint,
   \c!innermargin=\zeropoint,
   \c!setups=,
   \c!style=\v!normal,
   \c!color=,
   \c!textstyle=,
   \c!textcolor=,
   \c!align=,
   \c!number=\v!yes,
% \c!expansion=\v!no
% \c!prefix=\v!no,
% \c!prefixconnector=.,
% \c!way=\v!by\v!chapter,
% \c!prefixsegments=2:2,
% \c!way=\@@nrway,
% \c!blockway=\@@nrblockway,
% \c!sectionnumber=\@@nrsectionnumber,
% \c!separator=\@@koseparator,
% \c!starter=\@@kostarter,
% \c!stopper=\@@kostopper,
   \c!suffixseparator=, % currently rather hard coded
   \c!suffixstopper=, %% added
   \c!suffix=\floatcaptionsuffix,
   \c!distance=1em,
   \c!conversion=\v!numbers,
   \c!command=]

--
luigi