1.1. Terms

RDF data is represented as one of the followings:

• IRI: A generalization of URIs which allows the application of a wider range of Unicode characters.
• literal: A representation of values such as strings, and dates. Literals include two or three components:
  • A lexical form, providing the exact value.
  • A datatype IRI, to define the type of value (e.g. http://www.w3.org/2001/XMLSchema#string)
  • A language tag ONLY in case of having the datatype IRI as http://www.w3.org/1999/02/22-rdf-syntax-ns#langString.
• blank node: A non-specific representation. Having a blank node only provides the information that there exists a concept for the given relationship without explicit identification of it.

1.2. Triples

An RDF triple consists of:

• A subject which can be an IRI or a blank node
• A predicate which is an IRI
• An object which can be an IRI, a literal, or a blank node