Graph Data Model

A graph data model implies the notion of nodes and edges. In the graph data model, statements are represented as directed binary graphs – they always consist of  a subject node, a predicate edge and an object node.


Nodes can be

  1. a resource or the entry point of a resource,
  2. part of a resource (BNode), i.e. a subelement of a hierarchical description of a resources, e.g. a field in a MARCXML recordset (record), or
  3. simple value nodes, i.e. literals.

Attributes of Nodes

__NODETYPE__ Nodes always have a node type (__NODETYPE__). Node types are used for orientation in the graph data model. They can be any of these:

  • __RESOURCE__
  • __BNODE__
  • __LITERAL__
  • __TYPE_BNODE__
__URI__ if __NODETYPE__ == __RESOURCE__
__VALUE__ if __NODETYPE__ == __LITERAL__
__DATATYPE__ if __NODETYPE__ == __LITERAL__, the literal being a typified literal
__PROVENANCE__ if __NODETYPE__ == __RESOURCE__, the node type of the node not being __TYPE_RESOURCE__
__RESOURCE__ signifies the resource belonging to the node (in case it is a literal node or BNode)


A record is always a resource so the node type of the record’s entry node is __RESOURCE__. Resources or parts of resources can be typified. The types of resources are used as node labels in the graph:

  • a MABXML record, for instance, is of the type ‘Datensatz’ (record, and
  • a field within the MABXML record is of the type ‘Feld’ (field,

URIs are used as denominators for resource identifiers, types and attributes (predicates) of statements. All edges and resource nodes have a provenance attribute (__PROVENANCE__). It references the data model the statement or resource belongs to. Resource identifiers are connected with resource nodes by the attribute __URI__. Values of literals are connected with literal nodes by the attribute __VALUE__.


Edges are always attributes of resources or parts of resources, e.g. mabxml:nr (

Attributes of Edges

__RESOURCE__ Signifies the resource the node belongs to (if it is, for instance, a literal node or a BNode)
__ORDER__ Signifies the “In-Elements” order of values of a certain type, e.g. “mixed XML elements”
__INDEX__ Signifies the statement index of a resource (i.e. of the original element order as occurs in XML files)

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