XML 1.1

XML 1.1 (with XML Namespaces 1.1) originally extended XML 1.0 in three ways:

The second change has subsequently been retrofitted to XML 1.0 Fifth Edition (XML 1.0e5). Saxon now uses the XML 1.1 and XML 1.0e5 rules unconditionally for all validation of XML names.

XML 1.1 Input Documents

Saxon is capable of working with XML 1.1 input documents, provided that the XML parser supports XML 1.1.


If you want to use Saxon with XML 1.1, you should set the option -xmlversion:1.1 on the Saxon command line, or set the configuration option XML_VERSION.

This configuration setting affects:

Since Saxon 9.4, the configuration setting no longer affects:

Note that if you use the default setting of "1.0", then supplying an XML 1.1 source document as input may cause undefined errors.

It is advisable to use an XML parser that supports XML 1.1 when the configuration is set to "1.1", and an XML parser that does not support XML 1.1 when the configuration is set to "1.0". However, Saxon does not enforce this.

Data Model

In the XDM data model for representation of XML documents, it is possible to have namespaces that are in scope for a parent element, but not in scope for its children. This is supported by the native Saxon tree models (the TinyTree and LinkedTree), but not by most third-party tree models (DOM, XOM, JDOM2, etc). It is possible to create such trees using XSLT or XQuery, but they will never be produced by an XML 1.0 parser. Such trees can be serialized either as XML 1.0 or XML 1.1: if XML 1.0 is chosen, the namespace undeclarations used to indicate absent namespace bindings will simply be omitted from the output.

The choice of XML 1.0 or 1.1 also affects the set of characters permitted in strings, and in XML text and attribute nodes. Many (but not all) mechanisms for constructing strings check that if the configuration is set to XML 1.0, only permitted XML 1.0 characters may appear.


The serialization property version="1.0 | 1.1" may be set on the xsl:output and xsl:result-document elements, and on various APIs. The default depends on the setting in the Saxon Configuration.

You can set the configuration to allow XML 1.1, but still serialize result documents as XML 1.0 by specifying the output property version="1.0". In this case Saxon will check while serializing the document that it conforms to the XML 1.0 constraints (note that this check can be expensive). These checks are not performed if the configuration default is set to XML 1.0.

If you want the serializer to output namespace undeclarations, use the output property undeclare-namespaces="yes" as well as version="1.1".

It is not possible to serialize an XDM document as XML 1.0 if it contains text or attribute nodes using characters that XML 1.0 disallows.