  This document defines extensions of the RDF data model and of the SPARQL
query language that capture an alternative approach to represent
statement-level metadata. While this alternative approach is backwards
compatible with RDF reification as defined by the RDF standard, the approach
aims to address usability and data management shortcomings of RDF reification.
One of the great advantages of the proposed approach is that it clarifies a
means to (i) understand sparse matrices, the property graph model, hypergraphs,
and other data structures with an emphasis on link attributes, (ii) map such
data onto RDF, and (iii) query such data using SPARQL. Further, the proposal
greatly expands both the freedom that database designers enjoy when creating
physical indexing schemes and query plans for graph data annotated with link
attributes and the interoperability of those database solutions.
