Hello,
The date display is incorrect : I get day 28 instead of day 2.
Thank you
Fabrice

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     height=fit,
     width=fit]

  \definecolor[ColorA][0.8(white)]


  \startsetups [headertext]

    \setupheadertexts
      [{\startframed [headerframed]
      [foregroundstyle=bold,background=framewithshadow]
      \getvariable{headertext}{title}
n\high{o}\,\getvariable{headertext}{number}
      \stopframed}]

    \setupheadertexts
      [{\startframed [headerframed]
      [align=flushleft,foregroundstyle=]
       Lycée LA SALLE, Lille\\
       \getvariable{headertext}{location}
       \stopframed}]

      [{\startframed [headerframed]
          [align=flushright,foregroundstyle=]

\date[d=\getvariable{headertext}{day},m=\getvariable{headertext}{month},y=\getvariable{headertext}{year}]
          \stopframed}]

  \stopsetups

  \setvariable{headertext}{set}{\directsetup{headertext}}

\startuseMPgraphic{framewithshadow}
path p;
p:=origin--(OverlayWidth,0)--(OverlayWidth,OverlayHeight)--(0,OverlayHeight)--cycle;
fill p shifted (2,-2);
fill p withcolor 0.8white;
draw p;
setbounds currentpicture to p;
\stopuseMPgraphic

\defineoverlay[framewithshadow][\useMPgraphic{framewithshadow}]

\starttext
\setvariables
   [headertext]
   [title={Devoir maison},
    number={6},
    day={02},
    month={09},
    year={2019},
    location={Seconde B},
    time={}]
\input knuth
\stoptext