function onImage ( imagenm )
{
 if ( document.images )
 {
  document[imagenm].src = "http://if.digitalmzx.net/graphics/b_" + imagenm + "_hover.jpg";
 }
}

function offImage ( imagenm )
{
 if ( document.images )
 {
  document[imagenm].src = "http://if.digitalmzx.net/graphics/b_" + imagenm + "_off.jpg";
 }
}