Loterre aims to comply with the principles of LOD (Linked Open Data) as presented in 2006 by W3C (Tim Berners-Lee): terminology resources are considered here as organized sets of terms (designating concepts) that are freely accessible via semantic web technologies.

Linked Data or “web of linked data” is based on 4 basic rules:

1. Identify each resource (or concept) by a URI (Uniform Resource Identifier)
2. Use HTTP URIs (dereferenceable) to access information on these resources
3. When dereferencing a URI, return to structured data using the W3C family of standards: model (triplets RDF) and languages (SKOS, RDFS, OWL…) to describe them; SPARQL to query them
4. Link concepts (RDF data) belonging to different vocabularies or terminologies through alignments via their URIs, in order to create a network of RDF links and thus discover new relationships

By adding open licenses for the distribution and reuse of resources published on the web, Loterre complies with the rules of “Linked Open Data”.

T. Berners-Lee also proposed a progressive classification of LODs with 5 stars according to the following criteria:

* Data freely available on the web, with mention of an open license

** Data in a structured, machine-readable format

*** Non proprietary formats (CSV, JSON, …)

**** W3C open standards (RDF, XML, SPARQL) and URI as resource identifier

***** Data linked to other RDF data via alignments in the LOD Cloud

Finally, the resources integrated into the triplestore are intended, as far as possible, to comply with W3C best practices for the publication of related data (W3C, 2014).

All the resources exposed in Loterre are compatible with these rules and principles and can be classified as 4 or 5 stars:

• Free (lo) and/or open (CC BY) license
• Standard formats: SKOS, XML, JSON-LD, CSV
• Alignable URIs