XML Query Working Group Charter

The mission of the XML Query Working Group, part of the Extensible Markup Language (XML) Activity, is to provide flexible query facilities to extract data from XML and virtual documents, such as contents of databases or other persistent storage that are viewed as XML via a mapping mechanism, on the Web.

Join the XML Query Working Group.

End date 31 January 2013
Confidentiality Proceedings are Member-only
Initial Chair Jim Melton
Initial Team Contacts
(FTE %: 30)
Liam Quin
Usual Meeting Schedule Telcons: Weekly
Ftf: 2 or 3 per year (including TPAC).


The functionality of the XML Query language encompasses selecting whole documents or components of documents based on specified selection criteria, as well as constructing XML documents from selected components.

The goal of the XML Query Working Group is to produce and maintain a formal data model for XML documents with namespaces (based on the XML Information Set), a set of query functions and operators on that data model that is shared with XSLT, and then a query language with a concrete canonical syntax based on the proposed operators. The queries allowed by the query language should be computable and terminating. Such queries will act on fixed collections of XML documents. Functionalities include full-text text search (as opposed to simple substring search), updating instances of the query data model, and a set of XQuery Scripting Extensions intended to facilitate the use of XML Query in developing applications.

Success Criteria

The Working Group expects to demonstrate at least 2 interoperable implementations of all required and optional features of any new Specification before requesting to advance to Proposed Recommendation.


Note: to reduce confusion about version numbers, instead of a mix of 1.1 and 2.1 documents, the XSL and XQuery Working Groups agreed to renumber all the new versions as 3.0.

Jointly with the XSL Working Group, a set of W3C Recommendations for:

A set of W3C Recommendations for:

XQuery and XPath Full Text 1.0 and XQuery Update Facility 1.0 have been written to augment XPath 2.0 and XQuery 1.0. In a similar way, XQuery and XPath Full Text 3.0, XQuery Update Facility 3.0, and XQuery Scripting Extension 3.0 will augment XPath 3.0 and XQuery 3.0. The 3.0 versions of the Full Text and Update specifications are expected to be essentially the same as the 1.0 versions, but augment XQuery 3.0 and XPath 3.0 instead of 1.0.

Note: if the specifications had not been renumbered, Full Text 1.1 would have augmented XPath 2.1 and XQuery 1.1.

The following documents are expected to become Working Group Notes:

Other Deliverables

In addition, test suites will be developed, published and maintained for each specification expected to become a W3C Recommendation.

The XQuery Working Group may also publish requirements and/or use cases for future versions of their documents.

The XML Query WG and the XSL WG have been maintaining XQuery 1.0 and XPath 2.0 since their publication in Jan. 2007. These Recommendations were published as Second Editions in December 2010. It is possible that the WGs will publish additional editions of these Recommendations.

The XQuery Working Group may also update documents as appropriate to support validation using XML Schema (XSD) 1.1, as that specification progresses to Recommendation.

The design of the XQuery Scripting Extension has been difficult, and further design work may also be carried out in conjunction with other working Groups or with a Public Workshop.


Note: some technical problems arose as a result of impementation feedback for Full Text and for the Second Edition documents, which caused a long delay in publications in 2009 and 2010. The Working Group continued to be productive in other areas, however.

Specification FPWD LC CR PR Rec
Note: The group will document significant changes from this initial schedule on the group home page.
XQuery and XPath Full Text 1.0 N/A N/A N/A January 2011 March 2011
XQuery Update Facility 1.0 N/A N/A N/A February 2011 April 2011
XQuery 3.0 N/A May 2011 October 2011 February 2012 May 2012
XQueryX 3.0 N/A May 2011 October 2011 February 2012 May 2012
XML Path Language (XPath) 3.0 N/A May 2011 October 2011 February 2012 May 2012
XQuery 3.0 and XPath 3.0 Data Model N/A May 2011 October 2011 February 2012 May 2012
XQuery 3.0 and XPath 3.0 Functions and Operators N/A May 2011 October 2011 February 2012 May 2012
XSLT 3.0 and XQuery 3.0 Serialization N/A May 2011 October 2011 February 2012 May 2012
XQuery and XPath Full Text 3.0 April 2011 May 2011 October 2011 February 2012 May 2012
XQuery Update Facility 3.0 January 2011 May 2011 October 2011 February 2012 May 2012

Timeline View Summary


The expiration date of this charter is 31 January 2013.


W3C Groups

The XPath 1.0 language was developed by the XSL Working Group. The XPath 2.0 language was jointly developed by the XSL Working Group and the XML Query Working Group. The groups also jointly developed several other documents supporting XPath 2.0 and XSLT 2.0. The two groups will continue to collaborate on the development of XPath 2.1 and its supporting documents.
XML Schema
It is a goal of the XML Query work to be compatible with the work of the XML Schema Working Group on XML Schema Part 2: Datatypes (XML Schema Part 2) and XML Schema Part 1: Structures (XML Schema Part 1). For example, it should be possible to base query predicates on the existing DTD or XML Schema Part 1 definition of the content of an XML document and on the data types defined as part of W3C XML Schema Part 2.
XML Core
The XML Query work has defined and will extend a formal data model of XML documents. This model must be based on the model of the XML Infoset (XML Information Set). In case incompatibilities arise, requirements must be posed to the XML Core Working Group. In any case, the final model used by the XML Query working group will have to be based on, and totally compatible with, the model of the XML Infoset. In addition any XML Query definition of an XML fragment will take into consideration the XML Fragment Interchange specification (XML Fragment Interchange)
Internationalization Core
It is a goal of the XML Query work to ensure proper internationalization of the XML Query technology. The mission and scope of the Internationalization Working Group is to propose and coordinate any techniques, conventions, guidelines and activities within the W3C that help to make and keep the Web international. The XML Query Working Group and the Internationalization Working Group will work together to agree on specific I18N requirements and find solutions.

There are no requirements for co-development of features with the following Working Groups, but there are points of contact between their work and that of this Working Group, and thus logical dependency between their deliverables and those of this Working Group. Requirements from these Working Groups are expected to be well suited for communication via documents:

WAI Protocols & Formats Working Group
Reuse of common constructs greatly facilitates accessibility; the WAI PF Working Group will review work on the XML query facilities to be sure cost/benefit design decisions are informed of the benefits of accessibility.
RDF Data Access Working Group
The relationship with XQuery section mentions that the RDF DAWG should aim to maximize W3C technology re-use, such as using the XQuery 1.0 and XPath 2.0 Functions and Operators specification. The RDF Data Access Working Group and the XML Query Working Group will coordinate to ensure the reusability of the XQuery/XPath technologies.

When approved by the XML Coordination Group, liaison with other W3C Working Groups can be accomplished through joint task forces. It is expected that this be required for liaison with at least the XML Schema, XSL and Internationalization Working Groups.


To be successful, the XML Query Working Group is expected to have 6 or more active participants for its duration. Effective participation to XML Query Working Group is expected to consume half of a work day per week for each participant; two days per week for editors. The XML Query Working Group will allocate also the necessary resources for building Test Suites for each specification.

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


This group primarily conducts its work on the Member-only mailing list w3c-xsl-query@w3.org (archive) shared with the XSL Working Group, as well as various other lists: w3c-xsl-query-wg@w3.org (archive), member-query-fttf@w3.org (archive) and member-query-test@w3.org (archive). Public feedback happens through public-qt-comments@w3.org (archive).

Information about the group (deliverables, participants, face-to-face meetings, teleconferences, etc.) is available from the XML Query Working Group home page.

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 XML Query Working Group has been created according to section 6.2 of the Process Document. In the event of a conflict between the provisions of any charter and the W3C Process, the W3C Process shall take precedence.

This revision of the charter (2011) renames some documents from 1.1/2.1 to 3.0, and adjusts milestones as needed, but there are no new Recommendation Track deliverables.

Please also see the previous charter for this group.

Liam Quin, XML Activity Lead and Team Contact

$Date: 2011/02/07 23:12:21 $