Version 1.0 (1998); 5^th edition (2008)Dan Connolly and Jon Bosak formed the XML Working Group within the World Wide Web Consortium in the mid-1990s. Eleven members worked together on the design of the language, including Michael Sperberg-McQueen and James Clark. XML was notable for stemming from Standard Generalized Markup Language, but introducing several new features:

• An algorithm for encoding detection
• A processing instruction target
• The xml:space attribute
• Empty-element tags
• The standard of “well-formedness”rules for properly formatting markup language elements

Version 1.1 (2004)This version was published concurrently with the 3^rd edition of version 1.0, and is not intended as a replacement except in special cases. New features include:

• Enabling line-ending characters on EBCDIC platforms
• Compatibility for scripts added after Unicode 3.2the later editions of Version 1.0 also offer this ability

Version 2.0 (proposed)An early XML developer has proposed certain changes that would benefit a version 2.0:

• Eliminating DTDs (Document Type Definitions)
• Standardizing features that have developed since 1.0

1. Namespacesfor defining unique elements and attributes
2. XML Base for defining base Uniform Resource Identifiers (URIs)
3. XML Infoset for defining abstract data that can be used in other specifications

However, no work has been announced on a new version, and 1.0 5^th Edition remains the industry standard.