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OWL Working Group Charter

Status of this Document: On 6 September 2007 this document became the active charter of the new OWL Working Group.

The OWL Web Ontology Language is playing an important role in an increasing number and range of applications, and is the focus of research into tools, reasoning techniques, formal foundations and language extensions. The widespread use of OWL has revealed requirements for language extensions that are needed in applications. At the same time, research and development into reasoning techniques and practical algorithms has made it possible to provide tool support for language features that would not have been feasible at the time OWL was published.

The mission of the OWL Working Group, part of the Semantic Web Activity, is to produce a W3C Recommendation that refines and extends OWL. The proposed extensions are a small set that:

  1. have been identified by users as widely needed, and
  2. have been identified by tool implementers as reasonable and feasible extensions to current tools.

The OWL1.1 member submission, the list of postponed issues of the WebOnt Working Group, and the results and experiences of the OWLED Workshop series (Galway, 2005; Athens, 2006; Innsbruck, 2007) will form the basis of these extensions, but the Working Group will also consider other submissions.

Note that this charter uses the term “OWL 1.1” for easy reference. However, it is up to the Working Group to decide whether the final name of the extension will bear the name “OWL 1.1” or not, and whether the new features will be in the same namespace as the current OWL terms or not.

End date 1 July 2009
Confidentiality Proceedings are public
Initial Chairs Proposed: Ian Horrocks (Oxford University, UK)
Proposed: Alan Ruttenberg (ScienceCommons, MA, USA)
Initial Team Contacts
(FTE %: 50)
Sandro Hawke (35%)
Ivan Herman (Alternate, 15%)
Usual Meeting Schedule Teleconferences: Weekly
Face-to-face: between 2 and 4 per year


The extensions, referred to as OWL 1.1, fall into the following categories:

  • Extensions to the logic underlying OWL, adding new constructs that extend the expressivity of OWL (e.g., qualified cardinality restrictions and property chain inclusion axioms).
  • Extensions to the datatype support provided by OWL, e.g., with XML Schema Datatype semantics and datatype facets.
  • Additional syntactic facilities that do not extend the expressive power of OWL but that make some common modelling paradigms easier to express (e.g., disjoint unions).

The Working Group will also define a set of language fragments—profiles, or subsets of the language—that have been identified as having interesting or useful properties (e.g., being easier to implement). Fragments may include some of the extensions that the Working Group adopts. One of the first tasks of the Working Group will be to determine how subsets are to be defined.

The starting point for the Working Group is the OWL 1.1 member submission. There will also be an issues list, initially populated from the OWL 1.1 issues list, and the Working Group will also consider the list of postponed issues of the WebOnt Working Group.

Backwards compatibility with OWL is of great importance. For each new feature, if there is doubt or a perceived problem with respect to this issue, the guideline should be to not include the feature in the set of extensions. All new features should have a clear syntax, and a clear semantics both in terms of OWL DL and OWL Full. The existing compatibility between OWL DL and OWL Full should be preserved, and should be extended to new features wherever possible.

A detailed list of deliverables is provided in Section 2 below. The overall goal will be to ensure the easy adoption of OWL 1.1 features by OWL users and other members of the Semantic Web community.


The working group will deliver an Extended Web Ontology Language (OWL 1.1) specification as a W3C Recommendation. The specification will include (at least) the following components.

An introduction to the new language, including a clear explanation of its differences with respect to OWL.
A description of the goals and requirements that have motivated the design of OWL 1.1.
Formal specification:
A formal specification of the language's syntax and semantics (see, e.g., OWL Semantics and Abstract Syntax).
Descriptive specification:
A less formal, but still comprehensive and systematic, specification of the language's syntax and semantics (see, e.g., OWL Reference).
User guide:
Educational/outreach material aimed at (potential) users of the language (see, e.g., OWL Guide).
Test suite:
A set of test cases aimed at facilitating software development, and at illustrating design features and correct usage (see, e.g., OWL Test Cases).
Language Fragments:
A specification of one or more subsets of the language that have been identified as having interesting or useful properties.

Each component may consist of one or more documents, and may or may not extend existing OWL documents.

Other Deliverables

Other deliverables may include (at least):

  • XML Exchange syntax for OWL 1.1, with GRDDL enabled namespace document (to be decided by the group whether this document should go through the W3C Recommendation track or would be published as a W3C Note).
  • Additional outreach material aimed at easing the adoption of OWL 1.1 features by OWL users and other members of the Semantic Web community.


Note: The production of some of the deliverables may follow a slightly different timeline. The group will document these or any other schedule changes on the group home page.

Specification FPWD LC CR PR Rec
OWL?1.1 T+4 T+10 T+ 14 T+16 T+18

Timeline View Summary

  • Month T: First teleconference
  • Month T+2: First face-to-face meeting
  • Month T+4: First Public Working Draft for OWL 1.1
  • Month T+6: Second face-to-face meeting
  • Month T+10: Last Call for OWL 1.1
  • Month T+10: Third face-to-face meeting
  • Month T+14: Working Group Note for the XML Exchange syntax for OWL 1.1 (in case the WG decides to publish it separately as a note)
  • Month T+14: Fourth face-to-face meeting
  • Month T+14: Candidate Recommendation for OWL 1.1
  • Month T+16: Proposed Recommendation for OWL 1.1
  • Month T+18: OWL 1.1 Recommendation


W3C Groups

The OWL Working Group expects to maintain contacts with the following groups within W3C

Semantic Web Coordination Group
To ensure synchronization with all other Working and Interest Groups in the Semantic Web Activity
Rule Interchange Format (RIF) Working Group
To help produce the RIF Working Group deliverable on using RIF with OWL and generally avoid unnecessary difficulties for users working with RIF and OWL in combination
Semantic Web Deployment Working Group
To assist with questions concerning the interactions between OWL and Simple Knowledge Organisation System (SKOS)
Semantic Web Education and Outreach Interest Group
To synchronize possible OWL 1.1 outreach issues
Semantic Web Health Care and Life Sciences Interest Group
To consider the use case requirements possibly raised by the HCLS community when defining the various OWL 1.1 extensions
XML Schema Working Group
To ensure that the possible datatype support of OWL 1.1 is not incompatible with the XML Schema datatypes
Technical Architecture Group
To work with the group to ensure that the design is consistent with general Web architectural principles

Furthermore, the OWL Working Group expects to follow these W3C Recommendations:


To be successful, the OWL Working Group is expected to have 10 or more participants for its duration. Effective participation in the OWL Working Group is expected to consume one work day per week for each participant; two days per week for the editors. The OWL Working Group will also allocate the necessary resources for building Test Cases.

Participants are reminded of the Good Standing requirements of the W3C Process.


This group will conducts its technical work on the public mailing list public-owl-wg@w3.org. There may also be a Member-confidential mailing list used for administrative purposes.

Information about the group (deliverables, participants, face-to-face meetings, teleconferences, etc.) will be available from the OWL Working Group home page.

Decision Policy

As explained in the Process Document (section 3.3), this group will seek to make decisions when there is consensus. When the Chair puts a question and observes dissent, after due consideration of different opinions, the Chair should record a decision (possibly after a formal vote) and any objections, and move on.

Patent Policy

This Working Group operates under the W3C Patent Policy (5 February 2004 Version). To promote the widest adoption of Web standards, W3C seeks to issue Recommendations that can be implemented, according to this policy, on a Royalty-Free basis.

For more information about disclosure obligations for this group, please see the W3C Patent Policy Implementation.

About this Charter

This charter for the OWL Working Group has been created according to section 6.2 of the Process Document. In the event of a conflict between this document or the provisions of any charter and the W3C Process, the W3C Process shall take precedence.

Ivan Herman, W3C Semantic Web Activity Lead
Sandro Hawke, Proposed Staff Contact

$Date: 2007/09/07 15:35:51 $