anchor.diff:  linked data<<2>>.
   +
   .We check four criteria:
  -1.  Use URIs as names for things
  -+
  -We assume all subjects of statements are things. We search invalid
  -statement using a query described in Listing <<non_uri_subject, 10>>, and
  -if nothing is found the endpoint satisfied this rule.
  -+
  -Note that we ignore Virtuoso specific graphs since Virtuoso contains a
  -graph which contains invalid statements.
  -+
  -[[non_uri_subject]]
  -.Listing 10. A Query for searching non-URI subjects
  -....
  -SELECT
  -  *
  -WHERE {
  -GRAPH ?g { ?s ?p ?o } .
  -  filter (!isURI(?s) && !isBLANK(?s) && ?g NOT IN (
  -    <http://www.openlinksw.com/schemas/virtrdf#>
  -  ))
  -}
  -LIMIT 1
  -
  -....
  -2.  Use HTTP URIs so that people can look up those names
  +[start=2]
  +. Use HTTP URIs so that people can look up those names
   +
   We assume all subjects of statements are things. We search invalid
   statement using a query described in Listing
  
positive.code: LIMIT 1
  
  ....
  3.  When someone looks up a URI, provide useful information, using the
  standards (RDF*, SPARQL)
  +
  We assess this rule by obtaining a subject (URI) using a query described
  
negative.code: OFFSET 100
  
  ....
  . Include links to other URIs. so that they can discover more things
  +
  We assume the statement representing the link to other URI uses the
  vocabularies owl:sameAs or rdfs:seeAlso. We think if there are any
  