\starttext

    \enabletrackers[graphics.locating]

    \startMPrun{foo}
        beginfig(2) ;
            fill fullcircle scaled 1cm withcolor blue ;
        endfig ;
        beginfig(1) ;
            fill fullcircle scaled 2cm withcolor red ;
        endfig ;
    \stopMPrun

    \startMPrun
        beginfig(6) ;
            fill fullcircle scaled 15mm withcolor green ;
        endfig ;
    \stopMPrun

    \startoverlay
        {\externalfigure [mprun.foo.1]}
        {\externalfigure [mprun.6]}
        {\externalfigure [mprun:foo.2]}
    \stopoverlay

\stoptext
