function popUpFootnote(footNoteNumber){
    thisX = event.clientX + 15;
    thisY = event.clientY + document.body.scrollTop;
    thisIDName = "ID_footnote" + footNoteNumber + "";
    document.getElementById(thisIDName).style.posLeft = thisX;
    document.getElementById(thisIDName).style.posTop = thisY;
    document.getElementById(thisIDName).style.visibility = "visible";
}
function closeFootnote(footNoteNumber){
    thisIDName = "ID_footnote" + footNoteNumber + "";
    document.getElementById(thisIDName).style.visibility = "hidden";
}