Some pages, instead of embedding structured data, only provide a reference to it for example with rel="meta" http://patterns.dataincubator.org/book/autodiscovery.html Possibly also using rel="alternate" `<link rel="alternate" type="application/ld+json" href="https://graph.example/132131213"/> <link rel="alternate" type="text/turtle" href="https://graph.example/132131213"/> ` or rel="describes" `<link rel="describes" href="https://data.alice.example/12312321441#this"/>` maybe sniffer could try following all such links using appropriate content negotiation?