W3C has released Extensible Markup Language (XML) 1.1 as a Candidate Recommendation specification, signifying "that the document is believed to be stable, and to encourage implementation by the developer community. The specification addresses Unicode, control character, and line ending issues. Everything that is not forbidden is permitted in XML 1.1 names." XML 1.1 was known earlier as 'XML Blueberry'. The document "takes the form of a series of alterations to the XML 1.0 Recommendation, and its numbered sections correspond to those of the XML 1.0 Recommendation. Sections of that Recommendation that do not appear in this document remain unchanged in XML 1.1. It is likely that the final XML 1.1 Recommendation will take the form of an integral revision of the XML 1.0 specification." Interoperable implementations are being sought, and the W3C XML Core Working Group invites public comment on the draft.

Bibliographic information: Extensible Markup Language (XML) 1.1. W3C Candidate Recommendation 15-October-2002. Edited by John Cowan (Reuters). Version URL: http://www.w3.org/TR/2002/CR-xml11-20021015. Latest Version URL: http://www.w3.org/TR/xml11/. Previous Version URL: http://www.w3.org/TR/2002/WD-xml11-20020425/.

"The XML Core Working Group expects to request that the Director advance this specification to Proposed Recommendation after the XML Core Working Group documents at least two interoperable implementations. The two implementations must be produced by different organizations."

From the Introduction:

"... Whereas XML 1.0 provided a rigid definition of names, wherein everything that was not permitted was forbidden, XML 1.1 names are designed so that everything that is not forbidden (for a specific reason) is permitted. Since Unicode will continue to grow past version 3.1, further changes to XML can be avoided by allowing almost any character, including those not yet assigned, in names.

"In addition, XML 1.0 attempts to adapt to the line-end conventions of various modern operating systems, but discriminates against the conventions used on IBM and IBM-compatible mainframes. As a result, XML documents on mainframes are not plain text files according to the local conventions. XML 1.0 documents generated on mainframes must either violate the local line-end conventions, or employ otherwise unnecessary translation phases before parsing and after generation. Allowing straightforward interoperability is particularly important when data stores are shared between mainframe and non-mainframe systems (as opposed to being copied from one to the other). Therefore XML 1.1 adds NEL (#x85) to the list of line-end characters. For completeness, the Unicode line separator character, #x2028, is also supported.

"Finally, there is considerable demand to define a standard representation of arbitrary Unicode characters in XML documents. Therefore, XML 1.1 allows the use of character references to the control characters #x1 through #x1F, most of which are forbidden in XML 1.0. For reasons of robustness, however, these characters still cannot be used directly in documents. In order to improve the robustness of character encoding detection, the additional control characters #x7F through #x9F, which were freely allowed in XML 1.0 documents, now must also appear only as character references. (Whitespace characters are of course exempt.) The minor sacrifice of backward compatibility is considered not significant. Due to potential problems with APIs, #x0 is still forbidden both directly and as a character reference.

"A new XML version, rather than a set of errata to XML 1.0, is being created because the changes affect the definition of well-formed documents. XML 1.0 processors must continue to reject documents that contain new characters in XML names, new line-end conventions, and references to control characters. The distinction between XML 1.0 and XML 1.1 documents will be indicated by the version number information in the XML declaration at the start of each document.