rfc2413.txt

<VC++网络游戏建摸与实现>源代码

Network Working Group                                           S. Weibel
Request for Comments: 2413      OCLC Online Computer Library Center, Inc.
Category: Informational                                          J. Kunze
                                  University of California, San Francisco
                                                                C. Lagoze
                                                       Cornell University
                                                                  M. Wolf
                                                          Reuters Limited
                                                           September 1998


              Dublin Core Metadata for Resource Discovery

1. 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

   Copyright (C) The Internet Society (1998).  All Rights Reserved.

2. Abstract

   The Dublin Core Metadata Workshop Series began in 1995 with an
   invitational workshop which brought together librarians, digital
   library researchers, content experts, and text-markup experts to
   promote better discovery standards for electronic resources.  The
   Dublin Core is a 15-element set of descriptors that has emerged from
   this effort in interdisciplinary and international consensus
   building.  This is the first of a set of Informational RFCs
   describing the Dublin Core.  Its purpose is to introduce the Dublin
   Core and to describe the consensus reached on the semantics of each
   of the 15 elements.

3. Introduction

   Finding relevant information on the World Wide Web has become
   increasingly problematic due to the explosive growth of networked
   resources.  Current Web indexing evolved rapidly to fill the demand
   for resource discovery tools, but that indexing, while useful, is a
   poor substitute for richer varieties of resource description.

   An invitational workshop held in March of 1995 brought together
   librarians, digital library researchers, and text-markup specialists
   to address the problem of resource discovery for networked resources.




Weibel, et. al.              Informational                      [Page 1]

RFC 2413      Dublin Core Metadata for Resource Discovery September 1998


   This activity evolved into a series of related workshops and
   ancillary activities that have become known collectively as the
   Dublin Core Metadata Workshop Series.

   The goals that motivate the Dublin Core effort are:

       - Simplicity of creation and maintenance
       - Commonly understood semantics
       - Conformance to existing and emerging standards
       - International scope and applicability
       - Extensibility
       - Interoperability among collections and indexing systems

   These requirements work at cross purposes to some degree, but all are
   desirable goals.  Much of the effort of the Workshop Series has been
   directed at minimizing the tensions among these goals.

   One of the primary deliverables of this effort is a set of elements
   that are judged by the collective participants of these workshops to
   be the core elements for cross-disciplinary resource discovery.  The
   term "Dublin Core" applies to this core of descriptive elements.

   Early experience with Dublin Core deployment has made clear the need
   to support qualification of elements for some applications.  Thus, a
   Dublin Core element may be expressed without qualification (as
   described in this RFC) or with qualifiers that refine its semantics
   (the subject of future RFCs).  For the sake of interoperability,
   simple indexing and discovery tools should be able to ignore any
   qualifiers provided, while more advanced, semantically richer tools
   should be able to use qualifiers to support more specialized or
   precise discovery.

   The broad agreements about syntax and semantics that have emerged
   from the workshop series will be expressed in a series of
   Informational RFCs, of which this document is the first.

4. Description of Dublin Core Elements

   The following is the reference definition of the Dublin Core Metadata
   Element Set.  Further information about the Dublin Core Metadata
   Element Set is available at [1]:

       http://purl.org/metadata/dublin_core

   In the element descriptions below, each element has a descriptive
   name intended to convey a common semantic understanding of the
   element, as well as a formal single-word label intended to make the
   syntactic specification of elements simpler for encoding schemes.



Weibel, et. al.              Informational                      [Page 2]

RFC 2413      Dublin Core Metadata for Resource Discovery September 1998


   Although some environments, such as HTML, are not case-sensitive, it
   is recommended best practice always to adhere to the case conventions
   in the element labels given below to avoid conflicts in the event
   that the metadata is subsequently extracted or converted to a case-
   sensitive environment, such as XML (Extensible Markup Language) [2].

   Each element is optional and repeatable.  Metadata elements may
   appear in any order.  The ordering of multiple occurrences of the
   same element (e.g., Creator) may have a significance intended by the
   provider, but ordering is not guaranteed to be preserved in every
   system.

   To promote global interoperability, a number of the element
   descriptions suggest a controlled vocabulary for the respective
   element values.  It is assumed that other controlled vocabularies
   will be developed for interoperability within certain local domains.

   The metadata elements fall into three groups which roughly indicate
   the class or scope of information stored in them: (1) elements
   related mainly to the Content of the resource, (2) elements related
   mainly to the resource when viewed as Intellectual Property, and (3)
   elements related mainly to the Instantiation of the resource.

        Content          Intellectual Property       Instantiation
        -----------      ---------------------       -------------
        Title                 Creator                  Date
        Subject               Publisher                Format
        Description           Contributor              Identifier
        Type                  Rights                   Language
        Source
        Relation
        Coverage

4.1.  Title                             Label: "Title"

   The name given to the resource, usually by the Creator or Publisher.

4.2.  Author or Creator                 Label: "Creator"

   The person or organization primarily responsible for creating the
   intellectual content of the resource.  For example, authors in the
   case of written documents, artists, photographers, or illustrators in
   the case of visual resources.








Weibel, et. al.              Informational                      [Page 3]

RFC 2413      Dublin Core Metadata for Resource Discovery September 1998


4.3.  Subject and Keywords              Label: "Subject"

   The topic of the resource.  Typically, subject will be expressed as
   keywords or phrases that describe the subject or content of the
   resource.  The use of controlled vocabularies and formal
   classification schemes is encouraged.

4.4.  Description                       Label: "Description"

   A textual description of the content of the resource, including
   abstracts in the case of document-like objects or content
   descriptions in the case of visual resources.

4.5.  Publisher                         Label: "Publisher"

   The entity responsible for making the resource available in its
   present form, such as a publishing house, a university department, or
   a corporate entity.

4.6.  Other Contributor                 Label: "Contributor"

   A person or organization not specified in a Creator element who has
   made significant intellectual contributions to the resource but whose
   contribution is secondary to any person or organization specified in
   a Creator element (for example, editor, transcriber, and
   illustrator).

4.7.  Date                              Label: "Date"

   A date associated with the creation or availability of the resource.
   Recommended best practice is defined in a profile of ISO 8601 [3]
   that includes (among others) dates of the forms YYYY and YYYY-MM-DD.
   In this scheme, for example, the date 1994-11-05 corresponds to
   November 5, 1994.

4.8.  Resource Type                     Label: "Type"

   The category of the resource, such as home page, novel, poem, working
   paper, technical report, essay, dictionary.  For the sake of
   interoperability, Type should be selected from an enumerated list
   that is currently under development in the workshop series.

4.9.  Format                            Label: "Format"

   The data format and, optionally, dimensions (e.g., size, duration) of
   the resource.  The format is used to identify the software and
   possibly hardware that might be needed to display or operate the




Weibel, et. al.              Informational                      [Page 4]