Encoding Dublin Core Metadata in HTML
RFC 2731

Document Type RFC - Informational (December 1999; Errata)
Obsoleted by RFC 5791
Was draft-kunze-dchtml (individual)
Last updated 2013-03-02
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Network Working Group                                           J. Kunze
Request for Comments: 2731                                   Dublin Core
Category: Informational                              Metadata Initiative
                                                           December 1999

                 Encoding Dublin Core Metadata in HTML

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice


1. Abstract

   The Dublin Core [DC1] is a small set of metadata elements for
   describing information resources.  This document explains how these
   elements are expressed using the META and LINK tags of HTML
   [HTML4.0].  A sequence of metadata elements embedded in an HTML file
   is taken to be a description of that file.  Examples illustrate
   conventions allowing interoperation with current software that
   indexes, displays, and manipulates metadata, such as [SWISH-E],
   [freeWAIS-sf2.0], [GLIMPSE], [HARVEST], [ISEARCH], etc., and the Perl
   [PERL] scripts in the appendix.

2. HTML, Dublin Core, and Non-Dublin Core Metadata

   The Dublin Core (DC) metadata initiative [DCHOME] has produced a
   small set of resource description categories [DC1], or elements of
   metadata (literally, data about data).  Metadata elements are
   typically small relative to the resource they describe and may, if
   the resource format permits, be embedded in it.  Two such formats are
   the Hypertext Markup Language (HTML) and the Extensible Markup
   Language (XML); HTML is currently in wide use, but once standardized,
   XML [XML] in conjunction with the Resource Description Framework
   [RDF] promise a significantly more expressive means of encoding
   metadata.  The [RDF] specification actually describes a way to use
   RDF within an HTML document by adhering to an abbreviated syntax.

Kunze                        Informational                      [Page 1]
RFC 2731         Encoding Dublin Core Metadata in HTML     December 1999

   This document explains how to encode metadata using HTML 4.0
   [HTML4.0].  It is not concerned with element semantics, which are
   defined elsewhere.  For illustrative purposes, some element semantics
   are alluded to, but in no way should semantics appearing here be
   considered definitive.

   The HTML encoding allows elements of DC metadata to be interspersed
   with non-DC elements (provided such mixing is consistent with rules
   governing use of those non-DC elements).  A DC element is indicated
   by the prefix "DC", and a non-DC element by another prefix; for
   example, the prefix "AC" is used with elements from the A-Core [AC].

3. The META Tag

   The META tag of HTML is designed to encode a named metadata element.
   Each element describes a given aspect of a document or other
   information resource.  For example, this tagged metadata element,

       <meta name    = "DC.Creator"
             content = "Simpson, Homer">

   says that Homer Simpson is the Creator, where the element named
   Creator is defined in the DC element set.  In the more general form,

       <meta name    = "PREFIX.ELEMENT_NAME"
             content = "ELEMENT_VALUE">

   the capitalized words are meant to be replaced in actual
   descriptions; thus in the example,

             ELEMENT_NAME   was:  Creator
             ELEMENT_VALUE  was:  Simpson, Homer
             and PREFIX     was:  DC

   Within a META tag the first letter of a Dublin Core element name is
   capitalized.  DC places no restriction on alphabetic case in an
   element value and any number of META tagged elements may appear
   together, in any order.  More than one DC element with the same name
   may appear, and each DC element is optional.  The next example is a
   book description with two authors, two titles, and no other metadata.

       <meta name    = "DC.Title"
             content = "The Communist Manifesto">
       <meta name    = "DC.Creator"
             content = "Marx, K.">

Kunze                        Informational                      [Page 2]
RFC 2731         Encoding Dublin Core Metadata in HTML     December 1999

       <meta name    = "DC.Creator"
             content = "Engels, F.">
       <meta name    = "DC.Title"
             content = "Capital">

   The prefix "DC" precedes each Dublin Core element encoded with META,
   and it is separated by a period (.) from the element name following
   it.  Each non-DC element should be encoded with a prefix that can be
   used to trace its origin and definition; the linkage between prefix
   and element definition is made with the LINK tag, as explained in the
   next section.  Non-DC elements, such as Email from the A-Core [AC],
   may appear together with DC elements, as in

       <meta name    = "DC.Creator"
             content = "Da Costa, Jos&eacute;">
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