Or the lockin members 7 are provided with the inclinations projecting to a vertical face, and the board-shaped foundation part 2 is provided with the inclinations 2b inverse to those of the locking members. もしくは係止部材7は鉛直面に張り出し傾斜を設け、盤状基礎部2にはこれと逆の傾斜2bを形成した。 - 特許庁