function trim(s)
{
var start = 0;
var end = 1;
var slen = 0;

   while(s.charAt(start) == " ") start++;
   while(s.charAt(s.length - end) == " ") end++;

   slen = ((s.length - end) + 1);

   if (slen <= 0) {
     return "";
   } else {
     return s.substring(start, slen);
   }
}

function isDigit(c) {
  return (((c >= '0') && (c <= '9')) || (c=="."))
}

function isNumber(s)
{
var s2 = trim(s);
var i, len = parseInt(s2.length);

  if (len == 0)
    return false;

  for (i = 0; i < len; i++) {
    if (!isDigit(s2.charAt(i))) return false;
  }

  return true;
}

function isZero(s)
{
var s2 = trim(s);
var i, len = parseInt(s2.length);

  for (i = 0; i < len; i++) {
    if (s2.charAt(i) != '0') return false;
  }

  return true;
}

function disableButton(button,text)
{
  button.disabled=true;

  if (text != "") {
    button.value=text;
  }

}

function isValidDate(date)
{
  rex=/\b(1[0-2]|0?[1-9])\/(0?[1-9]|[12][0-9]|3[01])\/\d\d\d\d/
  return rex.test(date)
}