function validate_name(field,alerttxt){
  with (field) {
    if (value.length<2)
      {alert(alerttxt);return false;}
    else {return true;}
  }
}

function validate_email(field,alerttxt)
{
with (field)
  {
  apos=value.indexOf("@");
  dotpos=value.lastIndexOf(".");
  if (apos<1||dotpos-apos<2)
    {alert(alerttxt);return false;}
  else {return true;}
  }
}

function validate_form(thisform){
 with (thisform) {
  if (validate_name(cName,"Vul uw naam in")==false){
    cName.focus();
    return false;
    }
  if (validate_email(cMail,"Vul een geldig e-mail adres in")==false){
    cMail.focus();
    return false;
  }
  if (validate_name(cComment,"Wat is uw vraag of opmerking?")==false){
    cComment.focus();
    return false;
  }
 }
}