Changes Since December 2008

This page enumerates all the significant changes made to the OWL publications of 2 December 2008 (see announcement) and the versions we expect to publish in April 2009.

Note: LCC numbers refer to the working group's numbering of comments in response to the last call of 2 December 2008 as listed in Responses to Last Call Comments.

Significant Presentation Changes and New Documents

• Document Overview is a new non-normative document containing a high-level view of OWL (provided in response to LCCs 28, 52b, and others). Document Overview is meant to be read first amongst the OWL documents and provides a description of the various syntaxes and twin semantics of OWL 2, emphasizing the primacy of the RDF/XML exchange syntax for OWL 2. Document Overview also contains a guide to the OWL 2 document set.

• All OWL 2 documents now use a uniform terminology (in response to LCCs 28, 52b, and others). The most important terms used are:
  • OWL 2, a general term for all of OWL;
  • OWL 2 ontology, any OWL 2 ontology;
  • OWL 2 DL ontology, an OWL 2 ontology that can be viewed as a Description Logic knowledge base (and can be transformed from an RDF graph back to the OWL 2 functional syntax);
  • OWL 2 Full, an informal term meaning any RDF graph (and thus any OWL 2 ontology) under the OWL 2 RDF-based semantics; and
  • OWL 2 DL, an informal term meaning any OWL 2 DL ontology under the OWL 2 direct semantics.

• Primer has undergone a major rewrite, and is likely to undergo further changes.

• New Features and Rationale has undergone several editing changes in response to external comments and new working group reviews. It is is now more compact and clear, and its content is not likely to change much.

• Quick Reference Guide has undergone moderate editing to better present the syntax of OWL 2. There will be a reference card version of its content created shortly.

• RDF-Based Semantics has been completed and updated to reflect changes to OWL 2.

• Data Range Extension: Linear Equations is a new note describing an extension to OWL 2 providing linear equation conditions between the data values for an individual.

• Examples are now given as RDF graphs as well as in the functional syntax in Structural Specification and Functional Syntax, New Features and Rationale, and Primer (in response to LCCs 54 and others).

• In Structural Specification and Functional Syntax, the XML Schema datatypes defer their meaning to the XML Schema documents (as mentioned as a possibility in At Risk item number 2).

• Conformance has been renamed (was Conformance and Test Cases) and revised to make it clear that all OWL profiles can be interpreted according to either the direct semantics or the RDF-based semantics.

Technical changes to OWL 2

• The functional syntax in Structural Specification and Functional Syntax has been reverted back to a fully-typed syntax (in response to LCC 58).

• There are now explicit lists of the requirements to be an OWL 2 ontology and an OWL 2 DL ontology in the functional syntax given in Section 3 of Structural Specification and Functional Syntax (in response to LCCs 28 and 52b).

• The Functional Syntax, XML Serialization, and Manchester Syntax all use the SPARQL syntax for abbreviated IRIs instead of CURIES, which would have caused parsing problems, and use a SPARQL-like syntax for defining prefixes.

• All primitive XML Schema datatypes are pairwise disjoint in OWL 2, as in XML Schema datatypes (in response to LCCs 22 and 24).

• The datatype owl:realPlus is no longer useful (as an effect of the change in response to LCCs 22 and 24), and has been removed from OWL 2.

• The new XML Schema datatype xsd:dateTimeStamp is used in OWL 2 instead of owl:dateTime, as mentioned in At Risk item number 3.

• The semantics of xsd:dateTimeStamp is the XML Schema semantics instead of the previous special OWL 2 meaning. As a result xsd:dateTime is suitable for use in OWL 2 and has been added.

• It is now possible to define new, named datatypes as being equivalent to a data range expression (in response to LCCs 51, 62, and 65).

• The mapping from RDF graphs to the Functional Syntax in Mapping to RDF Graphs has been adjusted to reject malformed lists (in response to LCC 4).

• The mapping of property chains into RDF in Mapping to RDF Graphs has been adjusted to make it fit better with other RDF constructs (in response to LCC 34b).

• A new property, owl:versionIRI, is used for ontology version IRIs in RDF graphs instead of the previous owl:versionInfo, because owl:versionInfo is used for other purposes in some OWL ontologies.

• OWL 2 QL in Profiles now includes reflexive, irreflexive, and asymmetric property axioms (in response to LCCs 18 and 19).

• OWL 2 RL in Profiles now includes all the XML Schema datatypes that are in OWL 2 (in response to LCCs 20 and 43b).

• OWL 2 RL in Profiles now includes negative property assertions, assertions about class complements and the use of negated classes (ObjectComplementOf) in superclass expressions (in response to LCC 21).

• There is a new XML schema for the XML Serialization that can be better processed by XML tools (in response to LCC 40).

• The working group has committed to have a GRDDL transformation from the XML Serialization to RDF graphs which will be implemented during or before the candidate recommendation phase (in response to LCCs 17 and 34b).

Editorial Changes

• Most documents have had numerous minor editorial changes in response to LCCs and as a result of new working group reviews of the documents.

Still At Risk

• At Risk #1: support for owl:rational
• At Risk #4: support for rdf:XMLLiteral