W3CArchitecture Domain | XML

Charter - XSL Working Group

[June 2004]

Sharon Adler, IBM, chair
C. M. Sperberg-McQueen and Liam Quin, Team contacts

The XSL Working Group is a Working Group of the W3C and follows the working group process described in the W3C Process Document. Except as outlined elsewhere in this charter, the Working Group follows the Common Procedures for XML Working Groups.

This is the charter for this Working Group. It extends and supersedes the Working Group's previous charter. [N.B. Text which must be deleted or modified at the time this charter goes to the Advisory Committee, or which otherwise needs to be readily findable for revisions in the meantime (such as dates) is marked by square brackets.]

  1. Scope and Purpose
  2. Deliverables and Schedule
  3. Relationships with Other Activities
  4. Working Group participation
  5. Meetings
  6. Communications
  7. Confidentiality
  8. Patent policy

1. Scope and Purpose

Purpose of XSL

The XSL Working Group is chartered to continue the development of XSL (extensible stylesheet language), a style sheet and transformation language for XML and other structured markup languages.

The overall goal of this work is to define a practical style and transformation language capable of supporting the transformation and presentation of, and interaction with, structured information (e.g., XML documents) for use on servers and clients. The language is designed to build transformations in support of browsing, printing, interactive editing, and transcoding of one XML vocabulary into another XML vocabulary. To enhance accessibility, XSL is able to present information both visually and non-visually. XSL is not intended to replace CSS, but will provide functionality beyond that defined by CSS, for example, element re-ordering.

XSL is constituted of three main components, a transformation language known as XSLT, an expression language for addressing parts of XML documents, known as XPath, and a vocabulary of formatting objects with their associated formatting properties, known as XSL-FO.

Scope of the XSL Working Group

This charter defines the next phase in the continuing development of XSL. Both XSLT Version 1.0 and XPath Version 1.0 were published as W3C Recommendations in November 1999. XSL Formatting Objects became a W3C Recommendation in October 2001.

Under this charter, the XSL Working Group will continue work on XSLT and XPath 2.0 and work on a new version XSL Formatting Objects (XSL 1.1). The goal is to cope with the requirements that are not addressed yet by the first version.

XSLT and XPath

XSLT 2.0 is a language for transforming XML documents into other XML documents; it is intended to be used in conjunction with XPath 2.0. A transformation expressed in XSLT describes rules for transforming one or more source trees into one or more result trees. A transformation is specified through a set of template rules. The structure of result trees can be completely different from the structure of the source trees. In constructing a result tree, nodes from the source trees can be filtered and reordered, and arbitrary structure and content may be added. This mechanism allows a stylesheet to be applicable to a wide variety of source trees that have similar tree structures.

The major requirement for XSLT 2.0 and XPath 2.0 is to provide schema-awareness, so that simple datatypes and complex types defined using XML Schema may be visible to processors. It is also a requirement for transformations to take place without schema-awareness.

A series of working drafts of both XPath 2.0 and XSLT 2.0 have been published, beginning in December 2001. For XSLT, major differences from the 1.0 versions are summarized in Appendix K of the XSLT 2.0 specification. For XPath 2.0, Appendix H provides a summary of the main areas of incompatibility between XPath 2.0 and XPath 1.0.

XSL Formatting Objects

The XSL Working Group moved the XSL 1.0 specification of formatting objects to Recommendation on 15 October 2001.

The complex nature of the XSL specification leads to many questions and comments being posted to the public comment list by the growing XSL user and implementor community. The task of reviewing these comments and maintaining the XSL spec takes a non-trivial effort.

Since becoming a Recommendation, XSL 1.0 has enjoyed wide spread support. However, the user community has expressed requirements that have encouraged various implementations to provide extensions to the language. These extensions--especially those implemented by more than one implementation--are clear candidates for standardization so as to maximize interoperability.

For the period of this new charter, the XSL Working Group will continue to maintain the XSL Recommendation. The Working Group will also survey and analyze various extant extensions, user requirements, and features intentionally cut from XSL 1.0 due to lack of time. Using the results of this research, the Working Group will develop an XSL 1.1 version that incorporates current errata and includes a subset of relatively simple and upward compatible additions to XSL.

Where the functionality of CSS and XSL overlap, the style information shall be exportable in both XSL and CSS.

2. Deliverables and Schedule


The primary deliverables of the XSL Working Group under this charter are:

  1. Recommendation for XSLT 2.0
  2. Working jointly with the XML Query Working Group, recommendations for (a) XPath 2.0, (b) XQuery 1.0 and XPath 2.0 Data Model, (c) XQuery 1.0 and XPath 2.0 Formal Semantics, (d) XQuery 1.0 and XPath 2.0 Functions and Operators, and (e) XSLT 2.0 and XQuery 1.0 Serialization.
  3. A requirements document for version 1.1 of XSL formatting objects.
  4. Recommendation for version 1.1 of XSL formatting objects.
  5. Publication of any errata for XSLT 1.0 and XSL/FO 1.0
  6. A Web page, with minutes of each teleconference and face-to-face meeting.

The public release of each technical document has to be approved by the working group. Minutes are published under the Chair's responsibility.


This expected duration of this charter period runs through [June 2006].

During this charter period, the following documents will be published by the XSL Working Group. Some of these are expected to become W3C Recommendations; the requirements documents (listed below) will not.

The following documents are not expected to become W3C Recommendations:

3. Relationship with Other Activities

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, XML Query, and Internationalization Working Groups.

CSS Working Group

Liaison with the CSS group in the areas of Web stylesheet requirements is necessary in order to ensure that the market develops in a planned and unified fashion.

WAI Working Group

The XSL Working Group will cooperate with the Web Accessibility Initiative (WAI) to ensure XSL meets W3C accessibility goals. The WAI Working Group will provide expertise for work in this area and will review the specifications produced by the XSL Working Group.

I18N Working Group

Support for non-Western languages will continue to use the expertise of the I18N Working Group. In addition, the I18N Working Group will be solicited to comment on the new features added to XSLT, and check that they can be used to transform documents written in any language.

XML Query Working Group

The XPath 1.0 expression language was developed by the XSL Working Group in cooperation with the XML Linking Working Group. It has been an input to the development of XPath 2.0, which is being developed by the XSL and XML Query Working Groups in collaboration and will cover the functionality common to XQuery and XSLT.

XML Schema Working Group

It is a goal of work on XSLT 2.0 that it 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 for XPath expressions to exploit knowledge of XML Schema definitions of the content of an XML document and of the datatypes defined as part of XML Schema.

XForms Working Group

This Working Group produced a specification for extended forms (XForms). The XSL Working Group will have to consider how to handle these elements in combination with the XSL formatting objects. Cooperation with the XForms Working Group will be needed for that purpose, as well as consultation regarding their use of XPath.

Liaison with groups outside the W3C

The XSL Working Group is responsible for maintaining active communication with national and international standards bodies and industry consortia whose scope of work intersects its own. This specifically includes, but is not limited to, OASIS and IETF.

Media type registration

The XSL Working Group will work with other W3C Working Groups to determine the appropriate media type registration for XSL.

4. Working Group participation

The level of participation required for all participants in the XSL Working Group is 15-30% of their working time, including participation in regular phone conferences and face-to-face meetings.

Expertise in computer language design, web-based applications, XML, XPath/XSLT is optimal for participation in the development of XSLT. Expertise in composition, typography, computer display rendering and computer language design is recommended for participation in XSL formatting objects.


The initial Chair of the XSL Working Group is Sharon Adler (IBM).

W3C Team Resources

The initial W3C Team contacts for this Working Group are C. M. Sperberg-McQueen and Liam Quin. The total amount of resources is expected to be 0.6 FTE.

5. Meetings

Working Group phone conferences are held every week. When necessary to meet agreed-upon deadlines, additional phone conferences may be held. Separate phone conferences are held every other week for participants working on XSL formatting objects.

Face-to-face meetings are three- to four-day sessions held approximately six times per year. To maximize liaison between the Working Group and relevant standards bodies and vendor organizations, scheduled face-to-face meetings may be held in conjunction with major industry events and standards meetings. All face-to-face meetings are announced on the XSL Working Group page as well as on the XML CG and Member calendars.

6. Communications

XSL Working Group participants communicate via an archived mailing list, w3c-xsl-wg, visible to all W3C Members. During their development, all working documents must be visible to the W3C membership. In addition, there is a separate mailing list, w3c-xsl-fo-sg (archived), for discussion on XSL formatting objects; this list is Member-confidential.

7. Confidentiality

The proceedings of this Working Group are Member-confidential, subject to exceptions made by the Chair with the Working Group's agreement.

In support of public accountability, the Working Group will periodically make public a summary of all technical decisions made since the last public summary, and the rationales for these decisions.

8. 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.

Sharon Adler, Chair
Michael Sperberg-McQueen and Liam Quin, Team Contacts

Valid XHTML 1.0! Made with CSS