function IsNumeric(sText)
{
  // Note that this does not allow for decimal points.
  var ValidChars = "0123456789";
  var IsNumber=true;
  var Char;

  for (i = 0; i < sText.length && IsNumber == true; i++) 
    { 
    Char = sText.charAt(i); 
    if (ValidChars.indexOf(Char) == -1) 
       {
       IsNumber = false;
       }
    }
  return IsNumber;
 }