function vpurl(evt) {
	var charCode = evt.charCode;
	    if (!((charCode > 96 && charCode < 123) || (charCode > 64 && charCode < 91) || (charCode > 47 && charCode < 58) || charCode == 0 || charCode == 8 || charCode == 9 || charCode == 13 || charCode == 27 || charCode == 32 || charCode == 45 || charCode == 95 || charCode == 127)) {
	      evt.preventDefault();
	      alert("Please only use letters, numbers, hyphens and underscores");
	  }
	}