if (document.images) {	
	mezbuttonup       = new Image();
    mezbuttonup.src   = "img/internal--top-mez.png" ;
    mezbuttondown     = new Image() ;
    mezbuttondown.src = "img/internal--top-co-mez.png" ;
	
	bocbuttonup       = new Image();
    bocbuttonup.src   = "img/internal--top-boc.png" ;
    bocbuttondown     = new Image() ;
    bocbuttondown.src = "img/internal--top-co-boc.png" ;
	
	fivbuttonup       = new Image();
    fivbuttonup.src   = "img/internal--top-fiv.png" ;
    fivbuttondown     = new Image() ;
    fivbuttondown.src = "img/internal--top-co-fiv.png" ;
	
	citbuttonup       = new Image();
    citbuttonup.src   = "img/internal--top-cit.png" ;
    citbuttondown     = new Image() ;
    citbuttondown.src = "img/internal--top-co-cit.png" ;
}

function buttondown( buttonname )
{
    if (document.images) {
      document.getElementById(buttonname).src = eval( buttonname + "down.src" );
    }
}
function buttonup ( buttonname )
{
    if (document.images) {
      document.getElementById(buttonname).src = eval( buttonname + "up.src" );
    }
}