The term “namespace” is used here to imply the IRI where the elements in a named ontology or schema are defined and resolved. The namespace IRI reserved for xAPI is
https://w3id.org/xapi/ontology#. This reserved namespace IRI initially addresses xAPI vocabularies, but may be further expanded in the future to define a more complete ontological data model representation of other xAPI objects and properties as well.
Both namespaces and prefixes are practices carried over from XML schema design principles. Namespace prefixes provide a shorthand way of abbreviating long namespace IRIs, making the classes and properties that belong to a schema or ontology more readable and compact. For example, Verb defined as a Class in the xAPI Vocabulary Dataset Schema is identified by the IRI,
https://w3id.org/xapi/ontology#Verb and may also be represented as xapi:Verb, if the prefix xapi has been declared to stand for the namespace (
The namespace prefixes and their corresponding namespace IRIs currently used in this version of the xAPI Vocabulary Dataset Schema are provided below.
|Schema/Ontology Name||Prefix||Namespace IRI||Purpose for xAPI Vocabularies|
|Dublin Core||dcterms||http://purl.org/dc/terms/||for time/date versioning|
|Friend Of A Friend (FOAF)||foaf||http://xmlns.com/foaf/0.1/||for identifying the names of people or groups|
|Web Ontology Language (OWL)||owl||http://www.w3.org/2002/07/owl#||for ontology structure & modeling|
|Provenance Ontology (PROV-O)||prov||http://www.w3.org/ns/prov#||for vocabulary and term versioning and other maintenance metadata|
|Resource Description Framework (RDF)||rdf||http://www.w3.org/1999/02/22-rdf-syntax-ns#||for describing resources and their data types|
|RDF Schema||rdfs||http://www.w3.org/2000/01/rdf-schema#||for modeling resources with OWL classes & properties|
|Simple Knowledge Organization System (SKOS)||skos||http://www.w3.org/2004/02/skos/core#||for expressing relationships between concepts (e.g., verbs) and concept schemes (vocabularies)|
|Wordnet||wordnet||http://wordnet-rdf.princeton.edu/ontology#||for linking to synsets that can aid in word sense disambiguation and multilingual translations|
|Experience API (xAPI)||xapi||https://w3id.org/xapi/ontology#||to define xapi-specific classes and properties|
|XML Schema||xsd||http://www.w3.org/2001/XMLSchema#||for when using xsd data types such as date strings and language values|
Figure 4. Table of select namespaces used for xAPI Vocabulary datasets.