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W3.org has 287 URLs listed in 163 Dmoz categories.

DOM Level 3 XPath Specification
Provides simple functionalities to access a DOM tree using XPath 1.0. This module builds on top of the Document Object Model Level 3 Core. [W3C Working Draft 31 October 2001]
http://www.w3.org/TR/DOM-Level-3-XPath/
Top/Computers/Data_Formats/Markup_Languages/XML/Reference/Working_Drafts

XML Query Requirements
The goal is to produce a data model for XML documents, a set of query operators on that data model, and a query language based on these query operators. (W3C Working Draft 15 February 2001)
http://www.w3.org/TR/xquery-requirements/
Top/Computers/Data_Formats/Markup_Languages/XML/Reference/Working_Drafts

Associating Style Sheets with XML documents Version 1.0
W3C specification that allows a style sheet to be associated with an XML document by including one or more processing instructions with a target of xml-stylesheet in the document's prolog. (W3C Recommendation 29 June 1999)
http://www.w3.org/TR/xml-stylesheet/
Top/Computers/Data_Formats/Markup_Languages/XML/Style_Sheets

Extensible Stylesheet Language (XSL) 1.0
XSL is a language for expressing stylesheets. It consists of two parts: a language for transforming XML documents, and an XML vocabulary for specifying formatting semantics. (W3C Recommendation 15 October 2001)
http://www.w3.org/TR/xsl/
Top/Computers/Data_Formats/Markup_Languages/XML/Style_Sheets/XSL

XSLT Requirements Version 2.0
This draft document describes the requirements for the XSLT 2.0 specification. (W3C Working Draft 14 February 2001)
http://www.w3.org/TR/xslt20req
Top/Computers/Data_Formats/Markup_Languages/XML/Style_Sheets/XSL

XSL Transformations (XSLT) Version 1.0
This specification defines the syntax and semantics of XSLT, which is a language for transforming XML documents into other XML documents. (W3C Recommendation 16 November 1999)
http://www.w3.org/TR/xslt
Top/Computers/Data_Formats/Markup_Languages/XML/Style_Sheets/XSL

W3C : Extensible Stylesheet Language (XSL)
XSL information at W3C : this page is the starting point to all the official W3C documents about XSL.
http://www.w3.org/Style/XSL/
Top/Computers/Data_Formats/Markup_Languages/XML/Style_Sheets/XSL/Reference

XSL Transformation (XSLT) 1.0
The official XSL Transformations (XSLT) specification. XSLT is a language derived from XSL for transforming XML documents into other XML (or HTML) documents. (W3C Recommendation 16 November 1999)
http://www.w3.org/TR/xslt
Top/Computers/Data_Formats/Markup_Languages/XML/Style_Sheets/XSL/Reference

Voice Browsers - W3C Note
This note describes features needed for effective interaction with Web browsers that are based upon voice input and output.
http://www.w3.org/TR/NOTE-voice
Top/Computers/Data_Formats/Markup_Languages/XML/Tools/Browsers

DCD - Document Content Description for XML
This document proposes a structural schema facility, Document Content Description (DCD), for specifying rules covering the structure and content of XML documents. [W3C Note 31 July 1998]
http://www.w3.org/TR/NOTE-dcd
Top/Computers/Data_Formats/Markup_Languages/XML/Validation/Historical_Schema_Languages