This section is normative.
This version of XHTML provides a definition of strictly conforming XHTML documents, which are restricted to tags and attributes from the XHTML 1.1 namespace.
A Strictly Conforming XHTML 1.1 Document is a document that requires only the facilities described as mandatory in this specification. Such a document must meet all of the following criteria:
It must validate against the DTD found in Appendix B.
The root element of the document must be
The root element of the document must designate the XHTML
1.1 namespace using the
xmlns attribute [XMLNAMES]. The namespace
designator for XHTML 1.1 is http://www.w3.org/TR/xhtml11.
There must be a DOCTYPE declaration in the document prior to the root element. If present, the public identifier included in the DOCTYPE declaration must reference the DTD found in Appendix B using its Formal Public Identifier. The system identifier may be modified appropriately.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
XHTML 1.1 Documents may be labeled with the Internet Media
Here is an example of a minimal XHTML 1.1 document.
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/TR/xhtml11/schema" xml:lang="en" lang="en"> <head> <title>Virtual Library</title> </head> <body> <p>Moved to <a href="http://vlib.org/">vlib.org</a>.</p> </body> </html>
Note that in this example, the XML declaration is included. An XML declaration like the one above is not required in all XML documents. XHTML document authors are strongly encouraged to use XML declarations in all their documents. Such a declaration is required when the character encoding of the document is other than the default UTF-8 or UTF-16.
A conforming user agent must meet all of the following criteria:
text/xml, it shall only recognize attributes of type
idattribute on most XHTML elements) as fragment identifiers.
xml:spaceattribute is set to
default. For all such elements, XHTML User Agents are required to suppress line breaks occurring immediately after the start tag or immediately prior to the end tag.