Definitions of XML elements in this document use XML element type declarations (as found in XML Document Type Declarations), described in Section 3.2 of [W3C.REC-xml-20060816].
The namespace "urn:ietf:params:xml:ns:caldav" is reserved for the XML elements defined in this specification, its revisions, and related CalDAV specifications. XML elements defined by individual implementations MUST NOT use the "urn:ietf:params:xml:ns:caldav" namespace, and instead should use a namespace that they control.
The XML declarations used in this document do not include namespace information. Thus, implementers must not use these declarations as the only way to create valid CalDAV properties or to validate CalDAV XML element types. Some of the declarations refer to XML elements defined by WebDAV [RFC2518], which use the "DAV:" namespace. Wherever such XML elements appear, they are explicitly prefixed with "DAV:" to avoid confusion. Also note that some CalDAV XML element names are identical to WebDAV XML element names, though their namespace differs. Care must be taken not to confuse the two sets of names.
Processing of XML by CalDAV clients and servers MUST follow the rules described in [RFC2518]; in particular, Section 14, and Appendix 3 of that specification.