function isMail(mailField){
  strMail = mailField.value;
  var re = new RegExp;
  re = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
  var arr = re.exec(strMail);
  if (arr == null)
    return(false);
  else
    return(true);
}

function minLen(txtField, minVal){
  strExp = txtField.value;
  l = strExp.length;
  if (l < minVal)
    return(true);
  else
    return(false);
}

function maxLen(txtField, maxVal){
  strExp = txtField.value;
  l = strExp.length;
  if (l > maxVal)
    return(true);
  else
    return(false);
}

function isBlank(txtField){
  if (txtField.value)
    return (false);
  else
    return(true);
}

function isSelectedZero(txtField){
  selected = txtField.selectedIndex;
  if (selected == 0)
    return(true);
  else
    return(false);
}

function isNumber(txtField){
  numExp = txtField.value;
  if (isNaN(numExp) || (numExp.length == 0))
    return (false);
  else
    return(true);
}