public function getOrdinal(string $slatJointName): int
  {
    $ordinal = 0;
    $key     = null;
    foreach ($this->slatJoints as $key => $slat_joint)
    {
      if ($key==$slatJointName) break;

      $ordinal += $slat_joint->getColSpan();
    }

    if ($key!=$slatJointName)
    {
      throw new LogicException("SlatJoint '%s' not found.", $slatJointName);
    }

    return $ordinal;
  }