% try all characters on TEST.MF using the parameters of cmr10
if unknown cmbase: input cmbase fi % omit if CMMF can be assumed
mode_setup;

begingroup let fetch=input; save input;
 def input suffix t= enddef;
 fetch cmr10; font_setup;
endgroup;

let echar=endchar;
def endchar= echar; stop "done with character "&decimal charcode enddef;

input test;
end