abstractions manipulated by the WebDAV-specific HTTP methods
   described in section 8, "HTTP Methods for Distributed Authoring".

   In HTTP/1.1, method parameter information was exclusively encoded in
   HTTP headers. Unlike HTTP/1.1, WebDAV encodes method parameter
   information either in an Extensible Markup Language (XML) [REC-XML]
   request entity body, or in an HTTP header.  The use of XML to encode
   method parameters was motivated by the ability to add extra XML
   elements to existing structures, providing extensibility; and by
   XML's ability to encode information in ISO 10646 character sets,
   providing internationalization support. As a rule of thumb,
   parameters are encoded in XML entity bodies when they have unbounded
   length, or when they may be shown to a human user and hence require
   encoding in an ISO 10646 character set.  Otherwise, parameters are
   encoded within HTTP headers.  Section 9 describes the new HTTP
   headers used with WebDAV methods.

   In addition to encoding method parameters, XML is used in WebDAV to
   encode the responses from methods, providing the extensibility and
   internationalization advantages of XML for method output, as well as
   input.

   XML elements used in this specification are defined in section 12.

   The XML namespace extension (Appendix 4) is also used in this
   specification in order to allow for new XML elements to be added
   without fear of colliding with other element names.

   While the status codes provided by HTTP/1.1 are sufficient to
   describe most error conditions encountered by WebDAV methods, there
   are some errors that do not fall neatly into the existing categories.
   New status codes developed for the WebDAV methods are defined in
   section 10.  Since some WebDAV methods may operate over many




 
RFC 2518                         WEBDAV                    February 1999


   resources, the Multi-Status response has been introduced to return
   status information for multiple resources.  The Multi-Status response
   is described in section 11.

   WebDAV employs the property mechanism to store information about the
   current state of the resource.  For example, when a lock is taken out
   on a resource, a lock information property describes the current
   state of the lock. Section 13 defines the properties used within the
   WebDAV specification.

   Finishing off the specification are sections on what it means to be
   compliant with this specification (section 15), on
   internationalization support (section 16), and on security (section
   17).

2  Notational Conventions

   Since this document describes a set of extensions to the HTTP/1.1
   protocol, the augmented BNF used herein to describe protocol elements
   is exactly the same as described in section 2.1 of [RFC2068].  Since
   this augmented BNF uses the basic production rules provided in
   section 2.2 of [RFC2068], these rules apply to this document as well.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

3  Terminology

   URI/URL - A Uniform Resource Identifier and Uniform Resource Locator,
   respectively. These terms (and the distinction between them) are
   defined in [RFC2396].

   Collection - A resource that contains a set of URIs, termed member
   URIs, which identify member resources and meets the requirements in
   section 5 of this specification.

   Member URI - A URI which is a member of the set of URIs contained by
   a collection.

   Internal Member URI - A Member URI that is immediately relative to
   the URI of the collection (the definition of immediately relative is
   given in section 5.2).

   Property - A name/value pair that contains descriptive information
   about a resource.






 
RFC 2518                         WEBDAV                    February 1999


   Live Property - A property whose semantics and syntax are enforced by
   the server.  For example, the live "getcontentlength" property has
   its value, the length of the entity returned by a GET request,