A document comprised of structured data represented as sets of relations. These
relations are basically sets of tuples (representing entity relationships) grouped
by a predicate which indicates the entity relationship type. For instance, in a SQL
Relational Database Management system a Table Name functions as the Predicate. Whereas
in an RDF Predicate/Property Graph based Relational Database Management system (or store)
a Predicate is self-evident part Subject->Predicate->Object based 3-tuple.
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