function kp13 (field, event)
  {
    var i, kc = event.keyCode ? event.keyCode : event.which ? event.which : event.charCode, rc = true;

    if (kc == 13)
      {
        for (i = 0; i < field.form.elements.length; i++)
          {
            if (field == field.form.elements[i])
              break;
          }

        i = (i + 1) % field.form.elements.length;

        field.form.elements[i].focus();

        rc = false;
      }

    return rc;
  }