XML Processing Model Working Group Charter

The primary mission of the XML Processing Model Working Group, part of the Extensible Markup Language (XML) Activity, is to develop and maintain an XML-based pipeline language for orchestrating and specifying sequences and flows of operations to be performed upon XML documents.

Join the XML Processing Model Working Group.

End date 31 August 2017
Confidentiality Proceedings are public
Chair Norman Walsh
Team Contact
(FTE %: 5)
Liam Quin
Usual Meeting Schedule Teleconferences: Weekly as needed.
Face-to-face: TPAC plus 1-2 per year


The Working Group is hereby chartered to work on a new version of XProc: An XML Pipeline Language.

Requirements for the new version of XProc include better support for non-XML documents; this will facilitate working with JSON, EPUB, RDF/Turtle and other common non-XML formats in a mostly-XML workflow. See the XProc V2.0 Requirements document for other requirements; further work on requirements and use cases is of course also in scope.

The Working Group is chartered to maintain its existing documents as required.

Success Criteria

The Working Group will be considered successful if it can demonstrate multiple implementations of the new version of the XML Pipelining Language, XProc 2.0, during its charter period. It should be at Recommendation by the end of this charter period.


Other Deliverables

The Working Group will produce test suites for their specifications as needed to move through W3C Process and to promote interoperability.


Specification FPWD LC CR PR Rec
Note: The group will document significant changes from this initial schedule on the group home page.
XProc 2.0 Requirements and Use Cases [October 2013] N/A N/A N/A N/A
XProc 2.0 [December 2014] March 2015 June 2015 September 2016 December 2016

Relationship with Other Activities

The Digital Publishing Activity

Since XProc 1.0 and the XML toolchain it orchestrates are widely used in the publishing industry, informal liaison is encouraged; there are no Working Groups within the Activity at this time.

The XSLT and XQuery Working Groups

Informal liaison with the XSLT and XQuery Working Groups is to be encouraged, as well as with the Digital Publishing Activity, and the possibility of a Public Workshop is to be considered by the Working Group.

The Working Group is expected to monitor and be informed by streaming work in XSLT 3, so that streaming in XProc implementations is not precluded.

Within the XML Activity informal liaison between Working Groups is generally encouraged, and may be arranged as needed.


Participation is expected to consume one to three hours per week of each participant’s time (not including face to face meetings), although the time commitment for the chair and editors may be higher.

The level of participation expected for this Working Group suggests that representatives be experts in the development and use of XML-related specifications, as well as being W3C Members or Invited Experts.

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


The Working Group will have weekly teleconferences. Face-to-face meetings will be held up to three times per year.

This group primarily conducts its work on the public mailing list public-xml-processing-model-wg@w3.org (archive).

Information about the group (deliverables, participants, face-to-face meetings, teleconferences, etc.) is available from the XML Processing Model 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.

This charter is written in accordance with Section 3.4, Votes of the W3C Process Document and includes no voting procedures beyond what the Process Document requires.

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 Processing Model 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.

Please also see the previous charter for this group.

This charter was revised to permit work on a new version of the primary deliverable, the XProc language, and to bring the end-date into line with other Working Groups within the XML Activity.

Charter author: Liam R. E. Quin

$Date: 2015/09/16 04:02:04 $