Private Sub Workbook_SheetActivate(ByVal Sh As Object)
L = ActiveSheet.Range("IV4").End(xlToLeft).Column
ActiveSheet.Names.Add Name:="numero", RefersToR1C1:= _
"=R4C2:R4C" & L
ActiveSheet.Names.Add Name:="dimensions", RefersToR1C1:= _
"=R5C2:R5C" & L
ActiveSheet.Names.Add Name:="poids", RefersToR1C1:= _
"=R6C2:R6C" & L
End Sub