thank you very much Alain, I think I understood for the format "@d" but for other formats, I will need documentation. Fabrice \definecolor[mycolor][c=.4,m=0,y=0,k=0] \starttext \start \switchtobodyfont[small] \startMPcode xmin := 0; xmax := 22; ymax :=460 ;ymin:=0; u := 0.5cm; v:= 0.025cm; drawoptions(withpen pencircle scaled 0.5pt withcolor \MPcolor{mycolor}); draw hlingrid(ymin,ymax,20,11.5cm,11cm); draw vlingrid(xmin,xmax,2,11cm,11.5cm); drawoptions(withpen pencircle scaled 1pt) ; drawarrow (0,0)--(22,0) scaled u ; drawarrow (0,0)--(0,460) scaled v ; draw vlintext(0,20,2,10cm,"@d") shifted (0,-0.25cm) ; draw hlintext(0,420,20,11cm,"@d") shifted (-0.35cm,0) ; label.bot( "$x$",(10.8cm,-0.1cm)) ; label.lft( "$y$",(-0.1cm,11.4cm)) ; \stopMPcode \stop \stoptext