function DisplayCoords(MapImage)
  {
  var ImWidth=MapImage.width; var ImHeight=MapImage.height;
	
	//BOUNDARIES OF MAP IMAGE MUST BE CALIBRATED TO OS GRID

   var Emin=-225000; var Emax=690000;
   var Nmin=-37500; var Nmax=1287500;
  var Test = 'test';
  var Epix=event.offsetX;
  var Npix=event.offsetY;
  var IEast=Math.floor(Emin+(Emax-Emin)*(Epix/ImWidth));;
  var INorth=Math.floor(Nmin+(Nmax-Nmin)*(1-(Npix/ImHeight)));
  Alpha100km='VQLFAVQLFAWRMGBWRMGBXSNHCXSNHCYTOJDYTOJDZUPKEZUPKEVQLFAVQLFAWRMGBWRMGBXSNHCXSNHCYTOJDYTOJDZUPKEZUPKE';
  EastStr=''+Math.abs(IEast); NorthStr=''+Math.abs(INorth);
  while (EastStr.length<7) EastStr='0'+EastStr;
  while (NorthStr.length<7) NorthStr='0'+NorthStr;
  GR100km=eval(EastStr.substring(1,2)+NorthStr.substring(1,2));
  GRremainder=EastStr.substring(2,7)+' '+NorthStr.substring(2,7);
  Area='UK';
  if (Area=='UK')
    { // British Isles
    if (IEast<0 || INorth<0 || IEast>999999 || INorth>1499999)
      GR='outside British grid area';
    else
      {
      GR=Alpha100km.substring(GR100km,GR100km+1)+' '+GRremainder;
      HJ=(INorth>=1000000); TOJ=(IEast>=500000); ST=(INorth<500000);
      if (HJ)
        { if (TOJ) P='J'; else P='H'; }
      else
        {
        if (ST)
          { if (TOJ) P='T'; else P='S'; }
        else
          { if (TOJ) P='O'; else P='N'; }
        }
      GR=P+GR;
      }
    TetLet='AABBCCDDEEAABBCCDDEEFFGGHHIIJJFFGGHHIIJJKKLLMMNNPPKKLLMMNNPPQQRRSSTTUUQQRRSSTTUUVVWWXXYYZZVVWWXXYYZZ';
    GR1km=eval(EastStr.substring(3,4)+NorthStr.substring(3,4));
    TenKm=GR.substring(0,4)+GR.substring(9,10);
    Tetrad=TenKm+' '+TetLet.substring(GR1km,GR1km+1);
    Test= TenKm;
     if (Test == 'outstr')  window.status='Out of Range';
     else window.status='10 km Grid Square = '+TenKm;
    
    }

   
  }