function limitText(field, maxlen) 
    {
        if (field.value.length > maxlen)
            alert('Maximum length of field has been reached!');
        if (field.value.length > maxlen)
            field.value = field.value.substring(0, maxlen);
    }
function sizeImg(imgid)
    {
       PopEx(imgid,-30,-90,800,600,200,null);
    }
function changeImg(imgid,newSrc,tooltip)
    {
         var x = document.getElementById(imgid);
         x.src = newSrc; 
         x.alt = "Click to enlarge. " + tooltip;
    }