Network Working Group T. Hardie
Request for Comments: 2655 Equinix
Category: Experimental M. Bowman
Transarc
D. Hardy
Netscape
M. Schwartz
Affinia, Inc.
D. Wessels
NLANR
August 1999
CIP Index Object Format for SOIF Objects
Status of this Memo
This memo defines an Experimental Protocol for the Internet
community. It does not specify an Internet standard of any kind.
Discussion and suggestions for improvement are requested.
Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (1999). All Rights Reserved.
1. Abstract
The Common Indexing Protocol (CIP) allows servers to form a referral
mesh for query handling by defining a mechanism by which cooperating
servers exchange hints about the searchable indices they maintain.
The structure and transport of CIP are described in (Ref. 1), as are
general rules for the definition of index object types. This
document describes SOIF, the Summary Object Interchange Format, as an
index object type in the context of the CIP framework. SOIF is a
machine-readable syntax for transmitting structured summary objects,
currently used primarily in the context of the World Wide Web.
Query referral has often been dismissed as an ineffective strategy
for handling searches of Web resources, and Web resources certainly
present challenges not present in structured directory services like
Rwhois. In situations where a keyword-based free text search is
desired, query referral is not likely to be effective because the
query will probably be routed to every server participating in the
referral mesh. Where a search can be limited by reference to a
specific resource attribute, however, query referral is an effective
tool. SOIF can be used to create such a known-attribute query mesh
because it provides a method for associating attributes with net-
addressable resources.
Hardie, et al. Experimental [Page 1]RFC 2655 CIP Index Object Format for SOIF Objects August 1999
1.1 History
SOIF was first defined by the Harvest project [Ref 2.] in January
1994. SOIF was derived from a combination of the Internet Anonymous
FTP Archives IETF Working Group (IAFA) templates [Ref 3.] and the
BibTeX bibliography format [Ref 4.]. The combination was originally
noted for its advantages of providing a convenient and intuitive way
for delimiting objects within a stream, and setting apart the URL for
easy object access or invocation, while still preserving
compatibility with IAFA templates.
Mic Bowman, Darren Hardy, Mike Schwartz, and Duane Wessels each
contributed to the creation of the SOIF format as part of the Harvest
Project; later work took place as part of the FIND working group.
2. Name
The index object described below will have the MIME type of
application/index.obj.HARVEST-SOIF-1.
3. Payload Format
Each summary object has 3 fundamental components: a template type, a
URL, and zero or more ATTRIBUTE-VALUE pairs. Because the VALUEs in
the ATTRIBUTE-VALUE pairs may contain arbitrary data (cf. Section
3.5), SOIF objects should be encoded in Base64 unless the template
type unambiguously establishes that the VALUEs do not contain binary
data.
3.1 Template Type
The Template type is used to identify the set of ATTRIBUTEs contained
within a particular SOIF object. SOIF does not define the template
types themselves; it only provides a way to associate the summary
object with a predefined template type name. Template types may be
registered or unregistered. Unregistered template types provide an
indication of available ATTRIBUTE-VALUE pairs, but these may vary
both according to the original resource and the method by which the
summary object was generated. Registered template types must refer
to a formally specified description of all mandatory and optional
ATTRIBUTE-VALUE pairs available for that type. See [10] for a
description of the process of registering template types with the
IANA.
Historically, the template types used by SOIF were derived from IAFA
template types (Ref. 3). SOIF objects generated by the Harvest system
have a "FILE" template type; in current practice this is the most
common template type. The "FILE" template type is a generic template
Hardie, et al. Experimental [Page 2]
RFC 2655 CIP Index Object Format for SOIF Objects August 1999
type meant to handle a large variety of web-based resources. No
formal specification of it is available, though a list of ATTRIBUTE-
VALUE pairs common to the "FILE" template type is found in Appendix
A. "DOCUMENT" and "OBJECT" are other generic template-types.
The use of unregistered template types obviously presents some
problems to the correct operation of query referral. Two efforts
have been mounted to allow peer-to-peer agreement on the association
of template types with specific attribute sets: Netscape's RDM (Ref.
6) and the STARTS project (Ref. 7). Initially, CIP meshes based on
systems which use unregisterested template types may need to use
these or similar methods to associate template types with specific
attribute sets.
Mesh operators are strongly encouraged, however, to migrate to
registered template types as soon as is practical. Registered
template types allow CIP meshes to derive the definitions of
attributes, which enables multiple-language interfaces to the base
attributes. In addition, registered template types allow CIP meshes
and other users of SOIF to establish the permitted data types and
encodings of the VALUEs associated with each ATTRIBUTE. This makes
deriving the appropriate matching semantics for a particular VALUE
much more straightforward and eliminates the limitations of the
default octet-by-octet matching (cf. Section 4.).
3.2 URL
Uniform Resource Locators (URLs) (Ref 5.) are used by SOIF as object
IDENTIFIERs. SOIF associates its summary objects with net-
addressable resources by using the URL by which the resource was
addressed as the initial field of the object body. See section 3.4
for the formal grammar associated with SOIF objects.
This association allows the same resource to have multiple summary
objects, differentiated only by the URL by which the resource was
accessed. This possibility does not, however, impact the usability
of the URL as an object IDENTIFIER. Furthermore, since it can be
argued that the net address is a salient part of the metadata, there
may be compensating benefits to using the URL as an object
IDENTIFIER.
As noted in Appendix A, the Harvest project used several additional
identity attributes ("Gatherer-Name", "Gatherer-Host", "Gatherer-
Port" and "Gatherer-Version") to further identify the provenance of a
particular object. Within the context of CIP, it may be useful to
identify the base sources of particular index objects; see Appendix B
for one example of how a SOIF-based CIP hint could use the base
source URL.
Hardie, et al. Experimental [Page 3]RFC 2655 CIP Index Object Format for SOIF Objects August 1999
3.3 ATTRIBUTE-VALUE pairs.
Each summary object has zero or more ATTRIBUTE-VALUE pairs, which
contain metadata about the net-addressable resource referenced by the
URL. Pairs are composed of an ATTRIBUTE IDENTIFIER, the length of
the VALUE, a delimeter, and the VALUE. It should be stressed that
ATTRIBUTE VALUE pairs are not CR/LF terminated, but parsed according
to grammar set out in section 3.4. In the examples in Section 3.6
and in many other representations of SOIF objects, ATTRIBUTE-VALUE
pairs are represented on individual lines to enhance readability.
VALUEs may contain CR/LF, however, and implementors must be careful
to parse the full VALUE. Implementors of SOIF parsers MUST ignore
<CR>,<LF>,<TAB>,<SPACE>, or other whitespace found between the VALUE
of an ATTRIBUTE-VALUE pair and the ATTRIBUTE-IDENTIFIER of the
subsequent pair.
The SOIF syntax does not explicitly allow for a single ATTRIBUTE to
have multiple VALUEs. To handle multiple VALUEs for the same
ATTRIBUTE, SOIF uses an ATTRIBUTE naming convention; a hyphen and
positive integer are appended to the ATTRIBUTE name to create an
ATTRIBUTE IDENTIFIER VALUE associated with a specific ATTRIBUTE. For
example, the ATTRIBUTE IDENTIFIERs "Author-1", "Author-2", and
"Author-3" can be used to represent three VALUEs associated with the
ATTRIBUTE "Author" where a specific resource has three authors. See
section 4 for the implications of this strategy on matching
semantics.
3.4 SOIF Grammar
The SOIF syntax is defined by the following grammar:
SOIF ::= OBJECT SOIF |
OBJECT
OBJECT ::= @ TEMPLATE-TYPE { URL ATTRIBUTE-LIST }
TEMPLATE-TYPE ::= IDENTIFIER
ATTRIBUTE-LIST ::= ATTRIBUTE ATTRIBUTE-LIST |
ATTRIBUTE |
NULL
ATTRIBUTE ::= IDENTIFIER {VALUE-SIZE} DELIMITER VALUE
URL ::= RFC1738-URL-Syntax | "-"
IDENTIFIER ::= ALPHA-NUMERIC-STRING
VALUE ::= ARBITRARY-DATA
VALUE-SIZE ::= NUMERIC-STRING
DELIMITER ::= ":<TAB>"
Hardie, et al. Experimental [Page 4]RFC 2655 CIP Index Object Format for SOIF Objects August 1999
3.5 Grammar Description
URL
a Uniform Resource Locator encoded in the syntax defined by RFC
1738 [3]. If the summary object has no URL associated with it,
then a Latin-1 hyphen (octal \055) is used instead.
IDENTIFIER
an ASCII character string that only contains alphanumeric
characters and hyphens or underscores. IDENTIFIERs should avoid
including hyphens followed by positive integers except when
constructing multiple-VALUE ATTRIBUTE IDENTIFIERs.
VALUE
a buffer of VALUE-SIZE octets containing the VALUE. The VALUE may
contain data in arbitrary formats or encodings, which recipients
recognize based on Template-Type.
VALUE-SIZE
a non-negative integer encoded as an ASCII character string. The
integer indicates how many octets the VALUE occupies after the
DELIMITER.
DELIMITER
a two octet delimiter which is a Latin-1 colon (:) and a tab (\t),
(octal \072\011).
{ } the Latin-1 curly braces (octal \173 and \175) are used to wrap
the VALUE-SIZE (no spaces) as well as the URL and ATTRIBUTE-LIST
combination.
@TEMPLATE-TYPE
the Latin-1 @ (octal \100) and TEMPLATE-TYPE (no space between
them) is used to mark the beginning of the SOIF object.
NUMERIC-STRING
Zero or more ASCII numerals.
ALPHA-NUMERIC-STRING
Zero or more ASCII letters or numerals, plus hyphens or
underscore. [a-z,A-Z,0-9,- and _].
ARBITRARY-DATA
Octets of data in arbitrary formats or encodings.
Hardie, et al. Experimental [Page 5]RFC 2655 CIP Index Object Format for SOIF Objects August 1999
4. Matching Semantics
As was discussed in Section 1, query referral of SOIF objects will be
most effective when a query identifies a particular ATTRIBUTE or set
of ATTRIBUTEs as the target of the query match. A query-identified
ATTRIBUTE should be considered to match a SOIF ATTRIBUTE when a
case-insentive character-by-character comparison matches that portion
of the ATTRIBUTE IDENTIFIER prior to any hyphen-integer suffix. For
example, a query which asks for a match on the ATTRIBUTE "author"
should match the IDENTIFIERs "author", "Author", "AUTHOR", and
"Author-1". [10] discourages the registration of template types
containing ATTRIBUTEs which have previously been registered with
substantially different definitions. This will help eliminate mis-
referral, but a CIP mesh may nonetheless need to maintain a thesaurus
matching ATTRIBUTEs from particular template-types to those of other,
especially unregistered, template-types.
The matching semantics appropriate for a particular VALUE are derived
from its data type and encoding. For VALUEs associated with
ATTRIBUTEs which are part of a registered template type, the data
type and encoding are readily available. For VALUEs associated with
ATTRIBUTES associated with unregistered template-types, an octet-by-
octet comparison is the default. In cases where previous experience
has demonstrated that a particular ATTRIBUTE contains string data, a
case-insensitive substring match may be used. For example, in a
query against the "AUTHOR" ATTRIBUTE of the generic "DOCUMENT"
template type, the query VALUE "Garcia" should match the SOIF VALUEs
"Garcia", "GARCIA", and "Jose Garcia y Montes".
Over time, there may well emerge an understanding of which attributes
tend to produce correct query referrals within a mesh. As such
understandings emerge, mesh maintainers may wish to define a
particular SOIF TEMPLATE-TYPE which restricts included ATTRIBUTES to
those likely to foster correct referrals.
5. Internationalization
The internationalization of SOIF depends on the registration of
template-types. Since TEMPLATE-TYPEs and ATTRIBUTE IDENTIFIERs must
be in ASCII characters, only languages which use the ASCII character
set are fully supported for unregistered TEMPLATE-TYPEs. For
registered template types, in contrast, the specification of an
ATTRIBUTE's definition will allow UI designers to present a native-
language mapping of the ATTRIBUTE to the end user. Further, the
inclusion of data type and encoding information in the description of
VALUEs means that any language encoding or character set required by
a particular application may be supported. For unregistered template
types, the ability of peer servers to pass schema definitions may
Hardie, et al. Experimental [Page 6]
RFC 2655 CIP Index Object Format for SOIF Objects August 1999
provide a form of "private registration" which could provide some of
the facilities for internationalization available to registered
template types. (See above, section 3.1 and Refs. 6 and 7.)
6. Example Summary Objects
The appendices contain example summary objects encoded using specific
template types. The following are some example summary objects using
the generic "DOCUMENT" SOIF template-type:
@DOCUMENT { http://home.netscape.com:80/
Title{19}: Welcome to Netscape
Content-Type{9}: text/html
Content-Length{5}: 33262
}
@DOCUMENT { http://home.netscape.com/eng/ssl3/ssl-toc.html
Title{19}: SSL Protocol V. 3.0
Content-Type{9}: text/html
Content-Length{5}: 5870
Author-1{14}: Alan O. Freier
Author-2{14}: Philip Karlton
Author-3{14}: Paul C. Kocher
Abstract{318}: This document specifies Version 3.0 of the
<B>Secure Sockets Layer (SSL V3.0)</B> protocol, a security
protocol that provides communications privacy over the Internet.
The protocol allows client/server applications to communicate in
a way that is designed to prevent eavesdropping, tampering, or
message forgery.
}
@DOCUMENT { http://www.nissanmotors.com/1996/300ZX/pictures/300zx.jpg
Content-Type{10}: image/jpeg
Content-Length{5}: 25940
Last-Modified{31}: Tuesday, 11-Jun-96 19:18:44 GMT
Thumbnail{259}: ..................
}
7. Security
Please see (Ref. 1) for a general discussion of Security concerns for
the CIP framework.
SOIF currently contains no requirement that any template type contain
an authentication ATTRIBUTE. SOIF summary objects lacking
authentication ATTRIBUTEs must, therefore, be treated as unreliable
indicators of the referenced resource's content. A hostile party
could create a summary object which significantly misrepresented a
Hardie, et al. Experimental [Page 7]RFC 2655 CIP Index Object Format for SOIF Objects August 1999
resource's content. As part of a CIP mesh, this data could either
channel a large number of requestors to a resource (possibly
resulting in a denial of service) or away from a resource (possibly
resulting in a loss of appropriate visibility).
8. References
[1] Allen, J. and M. Mealling, "The Architecture of the Common
Indexing Protocol (CIP)", RFC 2651, August 1999.
[2] The Harvest Information Discovery and Access System:
<URL:http://harvest.transarc.com/>.
[3] D. Beckett, IAFA Templates in Use as Internet Metadata, 4th
Int'l WWW Conference, December 1995,
<URL:http://www.hensa.ac.uk/tools/www/iafatools/>
[4] L. Lamport, LaTeX: A Document Preparation System, Addison-
Wesley, Reading, Mass., 1986.
[5] Berners-Lee, T., Masinter, L. and M. McCahill, "Uniform Resource
Locators (URL)", RFC 1738, December 1994.
[6] D. Hardey, Resource Description Messages (RDM), W3C Note-rdm-
960724, July 24, 1996, <URL:http://www.w3.org/pub/WWW/TR/NOTE-
rdm.html>
[7] L. Gravano, K. Chang, H. Garcia-Molina, C. Lagoze, A. Paepcke,
STARTS: Stanford Protocol Proposal for Internet Retrieval and
Search, January 1997, <URL:http://www-
db.stanford.edu/~gravano/starts.html>
[8] S. Weibel, J. Kunze, C. Lagoze, Dublin Core Metadata for Simple
Resource Description, Work in Progress.
[9] E. Miller, Dublin Core Element Set Crosswalk, January 1997,
<URL:http://www.oclc.org:5046/~emiller/DC/crosswalk.html>
[10] Hardie, T., "Registration Procedures for SOIF Template Types",
RFC 2656, August 1999.
Hardie, et al. Experimental [Page 8]RFC 2655 CIP Index Object Format for SOIF Objects August 1999
9. Authors' Addresses
Ted Hardie
Equinix
901 Marshall Street
Redwood City, CA 94063 USA
EMail: hardie@equinix.com
Mic Bowman
Transarc Corporation
The Gulf Tower
707 Grant Street
Pittsburgh, PA 15219 USA
Phone: +1 412 338 4400
EMail: mic@transarc.com
Darren Hardy
Netscape Communications Corp.
685 E. Middlefield Road
Mountain View, CA 94043 USA
Phone: +1 415 937 2555
EMail: dhardy@netscape.com
Mike Schwartz
Affinia, Inc.
621 17th Street, Suite 1700
Denver, CO 80293
Phone: +1 (303) 292-4818
E-mail: mfs@affinia.net
Duane Wessels
National Laboratory for Applied Network Research
Phone: +1 303 497 1822
EMail: wessels@nlanr.net
Hardie, et al. Experimental [Page 9]
RFC 2655 CIP Index Object Format for SOIF Objects August 1999
Appendix A.
Common Attributes for "FILE" Template-type Summary Objects created by
Harvest:
Abstract
Brief abstract about the object.
Author
Author(s) of the object.
Description
Brief description about the object.
File-Size
Number of bytes in the object.
Full-Text
Entire contents of the object.
Gatherer-Host
Host on which the Gatherer ran to extract information from the
object.
Gatherer-Name
Name of the Gatherer that extracted information from the object.
(eg. Full-Text, Selected-Text, or Terse).
Gatherer-Port
Port number on the Gatherer-Host that serves the Gatherer's
information.
Gatherer-Version
Version number of the Gatherer.
Update-Time
The time that Gatherer updated the content summary for the object.
Keywords
Searchable keywords extracted from the object.
Last-Modification-Time
The time that the object was last modified.
MD5
MD5 16-byte checksum of the object.
Hardie, et al. Experimental [Page 10]RFC 2655 CIP Index Object Format for SOIF Objects August 1999
Refresh-Rate
The number of seconds after Update-Time when the summary object is
to be re-generated. Defaults to 1 month.
Time-to-Live
The number of seconds after Update-Time when the summary object is
no longer valid. Defaults to 6 months.
Title
Title of the object.
Type The object's type. Some example types are:
Archive
Audio
Awk
Backup
Binary
C
CHeader
Command
Compressed
CompressedTar
Configuration
Data
Directory
DotFile
Dvi
FAQ
FYI
Font
FormattedText
GDBM
GNUCompressed
GNUCompressedTar
HTML
Image
Internet-Draft
MacCompressed
Mail
Makefile
ManPage
Object
OtherCode
PCCompressed
Patch
Perl
PostScript
Hardie, et al. Experimental [Page 11]RFC 2655 CIP Index Object Format for SOIF Objects August 1999
RCS
README
RFC
SCCS
ShellArchive
Tar
Tcl
Tex
Text
Troff
Uuencoded
WaisSource
Update-Time
The time that the summary object was last updated. REQUIRED
field, no default.
URL-References
Any URL references present within HTML objects.
Appendix B.
Proposed Attributes for a "CIP-HINT" Template Type
Attribute-Identifier-List
A comma-delimited list whose entries take the form Template-
Type:Attribute . This list identifies the attributes against
which queries are supported. Because of the current limitation on
Identifiers, this list must be in ASCII.
Source
The URI of the service which created some or all of the index
objects to which this hint applies. Note that this service may be
and often is distinct from the server which provides query access
to those objects.
Total-Object-Count
The total number of index objects in the collection for which the
Hint applies. This should be a positive integer.
Weightlist-[Attribute-Identifier]
This construction allows the HINT to contain a weighted list of
values for a specific Attribute-Identifier. There may be as many
Weightlist entries as there Attribute-Identifiers in the
Attribute-Identifier-List. Each Weightlist entry takes the form
of Value;Object-Count, where the object count is a positive
integer representing the number of objects within the collection
which contain that value. Weightlists are comma- delimited.
Hardie, et al. Experimental [Page 12]RFC 2655 CIP Index Object Format for SOIF Objects August 1999
Should a Value contain a comma, it should be escaped when
incorporated into the weightlist.
Threshold-[Attribute-Identifier]
If a server wishes not to report infrequently occurring Values in
a specific Weightlist, it may declare a threshold under which it
will not report Values.
Certification-Type
The type of Certification used for this object
Certification
The Value of the Certification.
Date
The Date at which the hint was generated
Example:
@CIP-HINT{ http://nic.nasa.gov:80/Harvest/brokers/NASA/
Attribute-Identifier-list{49}:
DOCUMENT:Author, DOCUMENT:Keywords, IMAGE:Subject
Source-1{45}: http://nic.nasa.gov/Harvest/gatherers/Eureka/
Source-2{46}: http://techreports.larc.nasa.gov/cgi-bin/NTRS/
Total-Object-Count{5}: 10000
Weightlist-[IMAGE:Subject]{40}:
Shuttle;100, Planet;227, Moon;15, Sun;33
Threshold-[IMAGE:Subject]{2}: 10
Weightlist-[DOCUMENT:Author]{49}:
Grizzard;12, Aldrin\, Buzz;15, Aldrin\, James;45,
Threshold-[DOCMENT:Author]{1}: 5
Certification-Type{13}: PGP-Signature
Certification{51}: mQCNAzFNm5QAAEEALUBOolOWKpby+=YtmtBxUZWQgSGFyZGllID
Date{29}: Sun, 05 Jan 1997 08:33:33 GMT
}
Appendix C.
A "Dublin-Core" Template Type [Ref. 8,9]
TITLE
The name given to the resource by the CREATOR or PUBLISHER.
CREATOR
The person(s) or organization(s) primarily responsible for 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.
Hardie, et al. Experimental [Page 13]RFC 2655 CIP Index Object Format for SOIF Objects August 1999
SUBJECT
The topic of the resource, or keywords or phrases that describe
the subject or content of the resource. The intent of the
specification of this element is to promote the use of controlled
vocabularies and keywords. This element might well include
scheme-qualified classification data (for example, Library of
Congress Classification Numbers or Dewey Decimal numbers) or
scheme-qualified controlled vocabularies (such as Medical Subject
Headings or Art and Architecture Thesaurus descriptors) as well.
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. Future metadata
collections might well include computational content description
(spectral analysis of a visual resource, for example) that may not
be embeddable in current network systems. In such a case this
field might contain a link to such a description rather than the
description itself.
PUBLISHER
The entity responsible for making the resource available in its
present form, such as a publisher, a university department, or a
corporate entity. The intent of specifying this field is to
identify the entity that provides access to the resource.
CONTRIBUTOR
Person(s) or organization(s) in addition to those specified in the
CREATOR element who have made significant intellectual
contributions to the resource but whose contribution is secondary
to the individuals or entities specifed in the CREATOR element
(for example, editors, transcribers, illustrators, and convenors).
DATE
The date the resource was made available in its present form. The
recommended best practice is an 8 digit number in the form
YYYYMMDD as defined by ANSI X3.30-1985. In this scheme, the date
element for the day this is written would be 19961203, or December
3, 1996. Many other schema are possible, but if used, they should
be identified in an unambiguous manner.
TYPE
The category of the resource, such as home page, novel, poem,
working paper, technical report, essay, dictionary. It is
expected that RESOURCE TYPE will be chosen from an enumerated list
of types.
Hardie, et al. Experimental [Page 14]RFC 2655 CIP Index Object Format for SOIF Objects August 1999
FORMAT
The data representation of the resource, such as text/html, ASCII,
Postscript file, executable application, or JPEG image. The
intent of specifying this element is to provide information
necessary to allow people or machines to make decisions about the
usability of the encoded data (what hardware and software might be
required to display or execute it, for example). As with RESOURCE
TYPE, FORMAT will be assigned from enumerated lists such as
registered Internet Media Types (MIME types). In principal,
formats can include physical media such as books, serials, or
other non-electronic media.
IDENTIFIER
String or number used to uniquely identify the resource. Examples
for networked resources include URLs and URNs (when implemented).
Other globally-unique identifiers,such as International Standard
Book Numbers (ISBN) or other formal names would also be candidates
for this element.
SOURCE
The work, either print or electronic, from which this resource is
derived, if applicable. For example, an html encoding of a
Shakespearean sonnet might identify the paper version of the
sonnet from which the electronic version was transcribed.
LANGUAGE
Language(s) of the intellectual content of the resource. Where
practical, the content of this field should coincide with the NISO
Z39.53 three character codes for written languages.
RELATION
Relationship to other resources. The intent of specifying this
element is to provide a means to express relationships among
resources that have formal relationships to others, but exist as
discrete resources themselves. For example, images in a document,
chapters in a book, or items in a collection. A formal
specification of RELATION is currently under development. Users
and developers should understand that use of this element should
be currently considered experimental.
COVERAGE
The spatial locations and temporal durations characteristic of the
resource. Formal specification of COVERAGE is currently under
development. Users and developers should understand that use of
this element should be currently considered experimental.
Hardie, et al. Experimental [Page 15]RFC 2655 CIP Index Object Format for SOIF Objects August 1999
RIGHTS
The content of this element is intended to be a link (a URL or
other suitable URI as appropriate) to a copyright notice, a
rights-management statement, or perhaps a server that would
provide such information in a dynamic way. The intent of
specifying this field is to allow providers a means to associate
terms and conditions or copyright statements with a resource or
collection of resources. No assumptions should be made by users
if such a field is empty or not present.
Example:
@Dublin-Core-1 { ftp://ds.internic.net/internet-drafts/
draft-kunze-dc-00.txt
TITLE{52}: Dublin Core Metadata for Simple Resource Description
CREATOR-1{9}: S. Weibel
CREATOR-2{8}: J. Kunze
CREATOR-3{9}: C. Lagoze
SUBJECT{44}: The Dublin Core Set of Elements for Metadata
DESCRIPTION{46}: Reference description of Dublin Core elements.
PUBLISHER{31}: Internet Engineering Task Force
CONTRIBUTOR-1{11}: Nick Arnett
CONTRIBUTOR-2{15}: Eliot Christian
CONTRIBUTOR-3{14}: Martijn Koster
CONTRIBUTOR-4{18}: Christian Mogensen
CONTRIBUTOR-5{14}: Timothy Niesen
CONTRIBUTOR-6{11}: Andrew Wood
CONTRIBUTOR-7{10}: Mic Bowman
CONTRIBUTOR-8{11}: Dan Connoly
CONTRIBUTOR-9{15}: Michael Mauldin
CONTRIBUTOR-10{12}: Wick Nichols
DATE{16}: February 9, 1997
TYPE{14}: Internet draft
FORMAT{4}: Text
IDENTIFIER:{21} draft-kunze-dc-00.txt
SOURCE{41}: http://purl.oclc.org/metadata/dublin_core
LANGUAGE{3}: eng
RELATION{24}: Draft Reference Standard
COVERAGE{22}: Expires August 8, 1997
RIGHTS{58}: Unlimited Distribution;
readers must not cite as standard.
}
Hardie, et al. Experimental [Page 16]RFC 2655 CIP Index Object Format for SOIF Objects August 1999
11. Full Copyright Statement
Copyright (C) The Internet Society (1999). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
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followed, or as required to translate it into languages other than
English.
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Hardie, et al. Experimental [Page 17]
