<https://www.cosina.co.jp/voigtlander/vm-mount/#listItem>
<http://schema.org/position>
"3"^^<http://www.w3.org/2001/XMLSchema#integer>
<https://www.cosina.co.jp/voigtlander/vm-mount/nokton-vintage-line-50mm-f1-5-aspherical-ii/lh-6/>