function seleccionaCheckBox (objectID) {
  document.getElementById(objectID).checked = true;
}

function eventSeleccionaCheckBox (e,objectID) {
  var keynum;

	if(window.event) // IE
	{
		keynum = e.keyCode;
	}
	else if(e.which) // Netscape/Firefox/Opera
	{
		keynum = e.which;
	}
	if(keynum > 31 && keynum < 128) {document.getElementById(objectID).checked = true;}
}