Internet-Draft Herbert Van de Sompel Document: draft-vandesompel-info-uri-01.txt LANL Expires: June 2004 Tony Hammond Elsevier Eamonn Neylon Manifest Solutions Stuart L. Weibel OCLC December 2003 The "info" URI Scheme for Information Assets with Identifiers in Public Namespaces Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC 2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract This document defines the "info" Uniform Resource Identifier (URI) scheme for information assets with identifiers in public namespaces. Namespaces participating in the "info" URI scheme are regulated by an "info" Registry mechanism. Table of Contents 1 Introduction...................................................2 2 Terminology....................................................3 3 Application of the "info" URI Scheme...........................3 4 The "info" Registry............................................4 5 The "info" URI Scheme..........................................5 6 Normalization and Comparison of "info" URIs....................9 Van de Sompel Expires û June 2004 [Page 1]
The "info" URI Scheme December 2003 7 Rationale.....................................................11 8 Security Considerations.......................................12 9 Acknowledgements..............................................12 10 Normative References.......................................13 11 Non-Normative References...................................13 12 Authors' Addresses.........................................14 13 Full Copyright Statement...................................15 1 Introduction This document defines the "info" Uniform Resource Identifier (URI) scheme for information assets that have identifiers in public namespaces that are not part of the URI allocation. By information asset this document intends any information construct û i.e. any abstraction, manifestation or performance, whether digital or physical - that has identity within a public namespace. There exist many information assets with identifiers in public namespaces that are not referenceable by URI schemes. Examples of such namespaces include Dewey Decimal Classifications [DEWEY], Library of Congress Control Numbers [LCCN], NISO Serial Item and Contribution Identifiers [SICI], NASA Astrophysics Data System Bibcodes [BIBCODE], and National Library of Medicine PubMed identifiers [PMID]. Other candidate namespaces include Publisher Item Identifiers [PII], Online Computer Library Center OCLC Numbers [OCLCNUM], and NISO OpenURL Framework identifiers [OFI] amongst others. The "info" URI scheme facilitates the referencing of information assets that have identifiers in such public namespaces by means of URIs. When referencing an information asset by means of its "info" URI, the asset SHALL be considered a "resource" as defined in RFC 2396 [RFC2396] and SHALL enjoy the same common syntactic, semantic and shared language benefits that the URI presentation confers. As such, the "info" URI scheme enables public namespaces that are not part of the URI allocation to be represented within the allocation. The "info" URI scheme thus provides a bridging mechanism to allow public namespaces to become part of the URI allocation. Namespaces declared under the "info" URI scheme are regulated by an "info" Registry mechanism. The "info" Registry allows a public namespace that is not part of the URI allocation to be declared in a registration process by the organization that manages it (the Namespace Authority). The "info" Registry supports the declaration of public namespaces that are not part of the URI allocation in a manner that facilitates the construction of URIs for information assets without imposing the burdens of independent URI registration and maintenance of resource representations on the Namespace Authority. Information assets identified within a registered namespace SHALL be Van de Sompel Expires - June 2004 [Page 2]
The "info" URI Scheme December 2003 added or deleted according to the business processes of the Namespace Authority, and yet MAY be referenced within network applications via the "info" URI in an open, standardized way without additional action on the part of the Namespace Authority. The "info" URI scheme exists for identification purposes alone. Implementations MUST NOT assume that an "info" URI can be dereferenced to a representation of the resource identified by the URI. Applications of the "info" URI scheme are limited to the identification of information assets and the declaration of rules for comparing identity of such information assets regardless of whether any services relating to such information assets are accessible on the Internet. 2 Terminology In this document the key words "MUST", "MUST NOT", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "MAY", and "MAY NOT" are to be interpreted as described in RFC 2119 [RFC2119] and indicate requirement levels for compliant implementations. 3 Application of the "info" URI Scheme Public namespaces that are used for the identification of information assets, and that are not part of the URI allocation, MAY be registered as namespaces within the "info" Registry. Namespace Authorities MAY register these namespaces in the "info" Registry, thereby making these namespaces available to applications that need to reference information assets by means of a URI. Registrations of public namespaces that are not part of the URI allocation by parties other than the Namespace Authority SHALL NOT be permitted, thereby insuring against hostile usurpation or inappropriate usage of registered service marks or the public namespaces of others. Registration under the "info" Registry of a public namespace that is not part of the URI allocation implies no particular functionalities of the identifiers from the registered namespace other than the identification of information assets. No resolution mechanisms are associated with the "info" URI scheme, though for any particular namespace there MAY exist mechanisms for resolving identifiers to network services. The definition of such services falls outside the scope of the "info" URI scheme. Registration does not define namespace-specific semantics for identifiers within a registered namespace, though allowable character sets and normalization rules are specified in sections 5 and 6 so as to ensure that the URIs created using such identifiers are compliant with applications that use URIs. Van de Sompel Expires - June 2004 [Page 3]
The "info" URI Scheme December 2003 The registration of a public namespace in the "info" Registry SHALL NOT preclude further development of services associated with that namespace which MAY qualify the namespace for additional publication elsewhere within the URI allocation. 4 The "info" Registry The "info" Registry provides a mechanism for the registration of public namespaces that are used for the identification of information assets, and that are not part of the URI allocation. NISO [NISO], the National Information Standards Organization, will act as the Maintenance Agency for the "info" Registry, and will delegate the day-to-day operation of the "info" Registry to a Registry Operator. As the Maintenance Agency, NISO will ensure that the Registry Operator operates the "info" Registry in accordance with a publicly articulated policy document established under NISO governance and made available on the "info" website <http://info- uri.info/>. The "info" Registry policy defines a review process for candidate namespaces and provides measures of quality control and suitability for entry of namespaces. 4.1 Management Characteristics of the "info" Registry The "info" Registry will be managed according to policies established under the auspices of NISO. All such policies, as well as the namespace declarations in the "info" Registry, will be public. 4.2 Functional Characteristics of the "info" Registry The "info" Registry will be publicly accessible and will support discovery (by both humans and machines) of: . string literals identifying the namespaces . names and contact information of Namespace Authorities . syntax requirements for identifiers maintained in such namespaces . normalization methodology for identifiers maintained in such namespaces . ancillary documentation where the Registry entries refer to the corresponding "namespace" and "identifier" components which are defined in the ABNF given in section 5.1 of this document. 4.3 Maintenance of the "info" Registry The public namespaces that MAY be registered in the "info" Registry will be those of interest to the communities served by NISO and Van de Sompel Expires - June 2004 [Page 4]
The "info" URI Scheme December 2003 therefore NISO is committed to act as Maintenance Authority for the "info" Registry, and to assign a Registry Operator to operate it on a day-to-day basis. NISO, a non-profit association accredited by the American National Standards Institute (ANSI), identifies, develops, maintains, and publishes technical standards to manage information in the digital environment. NISO standards apply technologies to the full range of information-related needs, including retrieval, re-purposing, storage, metadata, and preservation. Founded in 1939, incorporated as a not-for-profit education association in 1983, and assuming its current name the following year, NISO draws its support from the communities it serves. The leaders of over 70 organizations in the fields of publishing, libraries, IT and media serve as its voting members. Hundreds of experts and practitioners serve on NISO committees and as officers of the association. NISO has been designated by ANSI to represent US interests to the International Organization for Standardization's (ISO) Technical Committee 46 on Information and Documentation. The NISO headquarters office is located at: 4733 Bethesda Ave., Bethesda, MD 20814, USA. (For further information, see the NISO website <http://www.niso.org/>.) 5 The "info" URI Scheme 5.1 Definition of "info" URI Syntax Note: RFC 2396, "Uniform Resource Identifiers (URI): Generic Syntax" [RFC2396] is being revised [2396BIS] at the time of this writing. The syntax used in this document follows the revisions made to the generic URI syntax defined in RFC 2396 [2396BIS]. The "info" URI syntax presented in this document is generally conformant with the generic URI syntax defined in RFC 2396 [RFC2396]. The only point of departure is to make use of the new "segment" production as generalized in the revision to RFC 2396 [2396BIS]. This specification uses the Augmented Backus-Naur Form (ABNF) notation of RFC 2234 [RFC2234] to define the URI. The following core ABNF productions are used by this specification as defined by Section 6.1 of RFC 2234: ALPHA, DIGIT, HEXDIG. The "info" URI syntax is presented in two parts. Part A contains productions specific to the "info" URI scheme, while Part B contains generic productions from the RFC 2396 revision [2396BIS] which are Van de Sompel Expires - June 2004 [Page 5]
The "info" URI Scheme December 2003 repeated here both for completeness and for reference. (Although the work on revising RFC 2396 is currently ongoing we expect that the productions presented here will coincide with the final outcome of that work. Nevertheless this BNF is complete in itself.) The following set of productions (Part A) are specific to the "info" URI scheme: ; Part A: ; productions specific to the "info" URI scheme info-URI = info-scheme ":" info-identifier [ "#" fragment ] info-scheme = "info" info-identifier = namespace "/" identifier namespace = scheme identifier = path-segments Note that the "info-identifier" production is a restriction on the "rel-path" branch of the "hier-part" production in the RFC 2396 revision [2396BIS]. Further note that relative URI forms for "info" URIs SHOULD NOT be allowed. This next set of productions (Part B) are generic productions reproduced from the RFC 2396 revision [2396BIS]: ; Part B: ; generic productions from the RFC 2396 revision [2396BIS] scheme = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." ) path-segments = segment *( "/" segment ) segment = *pchar fragment = *( pchar / "/" / "?" ) pchar = unreserved / escaped / ";" / ":" / "@" / "&" / "=" / "+" / "$" / "," unreserved = ALPHA / DIGIT / mark escaped = "%" HEXDIG HEXDIG mark = "-" / "_" / "." / "!" / "~" / "*" / "'" / "(" / ")" Van de Sompel Expires - June 2004 [Page 6]
The "info" URI Scheme December 2003 An "info" URI has an "info-identifier" as its scheme-specific part and MAY take an optional "fragment" component. An "info-identifier" is constructed by appending an "identifier" component to a "namespace" component separated by a slash "/" character. The "info" URI scheme supports hierarchy as indicated by the presence of the slash "/" character. The intent of any slash "/" character within the "identifier" component SHALL be construed as representing a hierarchy delimiter, regardless of the intent of that character in the original namespace. Values for the "namespace" component of the "info" URI are name tokens composed of URI scheme characters only (cf. the "scheme" production). They identify the public namespace in which the (unescaped) value for the "identifier" component originates, and are registered in the "info" Registry, which guarantees their uniqueness. Although the "namespace" component is case-insensitive, the canonical form is lowercase and documents that specify values for the "namespace" component MUST do so using lowercase letters. An implementation SHOULD accept uppercase letters as equivalent to lowercase in "namespace" names, for the sake of robustness, but SHOULD only generate lowercase "namespace" names, for consistency. Values for the "identifier" component of the "info" URI are hierarchical strings composed of path segments of path segment characters (cf. the "pchar" production), the segments being separated by slash "/" characters. In their originating public namespace, the (unescaped) values for the "identifier" component identify information assets. The values for the "identifier" component MUST be %-escaped as required by this syntax. The "identifier" component MUST be treated as case-sensitive, although the "info" Registry MAY record the case-sensitivity of identifiers from within particular registered public namespaces. The "info" Registry MAY also disclose additional normalization rules regarding the treatment of punctuation characters and the like. Values for the "fragment" component of the "info" URI are strings composed of path segment characters (cf. the "pchar" production) plus the slash "/" character and the question-mark "?" character. No semantic role is assigned to the the slash "/" character and the question-mark "?" character within the "fragment" component. The (unescaped) values for the "fragment" component identify secondary information assets with respect to the primary information asset which is referenced by the "info-identifier". The values for the "fragment" component MUST be %-escaped as required by this syntax. The "fragment" component MUST be treated as case-sensitive. 5.2 Allowed Characters Under the "info" URI Scheme Van de Sompel Expires - June 2004 [Page 7]
The "info" URI Scheme December 2003 The "info" URI syntax uses the same set of allowed US-ASCII characters as specified in RFC 2396 [RFC2396] for a generic URI. An "info" URI string SHOULD be represented as a UNICODE [UNICODE] string and be encoded in UTF-8 [RFC2279] form. Reserved characters as well as excluded US-ASCII characters and non-US-ASCII characters MUST be %-escaped before forming the URI. Details of the %-escape encoding can be found in RFC 2396, section 2.4. 5.3 Examples of "info" URIs Some examples of syntactically valid "info" URIs are given below: a) info:ddc/22/eng//004.678 where "ddc" is the "namespace" component for a Dewey Decimal Classification [DEWEY] namespace and "22/eng//004.678" is the "identifier" component for an identifier of an information asset within that namespace. The information asset identified by the identifier "22/eng//004.678" in the namespace for (22nd Ed.) English-language Dewey Decimal Classifications is the classification "Internet" b) info:lccn/2002022641 where "lccn" is the "namespace" component for a Library of Congress Control Number [LCCN] namespace and "2002022641" is the "identifier" component for an identifier of an information asset within that namespace. The information asset identified by the identifier "2002022641" in the namespace for Library of Congress Control Numbers is the book "Newcomer, Eric. Understanding Web services: XML, WSDL, SOAP, and UDDI. Boston: Addison-Wesley, 2002." c) info:sici/0363-0277(19950315)120:5%3C%3E1.0.TX;2-V where "sici" is the "namespace" component for a of Serial Item and Contribution Identifier [SICI] namespace and "0363- 0277(19950315)120:5%3C%3E1.0.TX;2-V" is the "identifier" component for an identifier of an information asset in that namespace in %- escaped form, or in unescaped form "0363- 0277(19950315)120:5<>1.0.TX;2-V". Van de Sompel Expires - June 2004 [Page 8]
The "info" URI Scheme December 2003 The information asset identified by the identifier "0363- 0277(19950315)120:5<>1.0.TX;2-V" in the namespace for Serial Item and Contribution Identifiers is the journal issue "Library Journal, Vol. 120, no. 5. March 15, 1995." d) <rdf:Description about="info:bibcode/2003Icar..163..263Z"/> where "bibcode" is the "namespace" component for a NASA ADS Bibcode [BIBCODE] namespace and "2003Icar..163..263Z " is the "identifier" component for an identifier of an information asset within that namespace. This example further shows an application of an "info" URI as the subject of an RDF statement. The information asset identified by the identifier "2003Icar..163..263Z" in the namespace for NASA ADS Bibcodes is the abstract of the journal article "K. Zahnle, P. Schenk, H. Levison and L. Dones, Cratering rates in the outer Solar System, Icarus, 163 (2003) pp. 263-289." e) info:pmid/12376099 where "pmid" is the "namespace" component for a PubMed Identifier [PMID] namespace and "12376099" is the "identifier" component for an identifier of an information asset in that namespace. The information asset identified by the identifier "12376099" in the namespace for PubMed Identifiers is the abstract of the journal article "Wijesuriya SD, Bristow J, Miller WL. Localization and analysis of the principal promoter for human tenascin-X. Genomics. 2002 Oct;80(4):443-52." 6 Normalization and Comparison of "info" URIs In order to facilitate comparison of "info" URIs, a sequence of normalization steps SHOULD be applied. Since the "info" URI is case-sensitive, a canonical form MAY only be arrived at by consulting the "info" Registry for possible information on the case-sensitivity for identifiers from a registered public namespace, and any case normalization step to apply. The "info" Registry MAY also disclose additional normalization rules regarding the treatment of punctuation characters and the like. The following generic normalization steps SHOULD be applied: Van de Sompel Expires - June 2004 [Page 9]
The "info" URI Scheme December 2003 a) Normalize the case of the "scheme" component to be lowercase b) Normalize the case of the "namespace" component to be lowercase c) Unescape all unreserved %-escaped characters in the "namespace" and "identifier" components d) Normalize the case of any %-escaped characters in the "namespace" and "identifier" components to be uppercase The subsequent namespace-specific normalization steps MAY be applied: e) Normalize the case of the "identifier" component as per any rules that may be recorded in the Registry f) Normalize any punctuation characters in the "identifier" component as per any rules that may be recorded in the Registry Note that the "info" URI scheme provides a relative path only for its hierarchical part, and as such any path normalization of dot segments ("/./" and "/../") MUST NOT be applied. The following unnormalized forms of an "info" URI U1. INFO:PII/S0888-7543(02)96852-7 U2. info:PII/S0888754302968527 U3. info:pii/S0888%2D7543%2802%2996852%2D7 U4. info:pii/s0888-7543(02)96852-7 are normalized to the following respective forms N1. info:pii/S0888-7543(02)96852-7 N2. info:pii/S0888754302968527 N3. info:pii/S0888-7543(02)96852-7 N4. info:pii/s0888-7543(02)96852-7 If the "info" Registry records the case-sensitivity for identifiers from the "pii" registered public namespace as being case-insensitive and normalized to an uppercase form, then the above URI forms can be reduced to the following forms N1,N3. info:pii/S0888-7543(02)96852-7 N2. info:pii/S0888754302968527 If the "info" Registry further records the treatment of punctuation characters for identifiers from the "pii" registered public namespace as being optional and normalized to a punctuation free form, then the above URI forms can be reduced to the following unique canonical form Van de Sompel Expires - June 2004 [Page 10]
The "info" URI Scheme December 2003 N2. info:pii/S0888754302968527 If the "info" URI includes a "fragment" component, namespace-specific normalization steps MUST NOT be applied to the "fragment". This would result in being unable to reconcile the following two URI forms N2a. info:pii/S0888754302968527#sec4 N2b. info:pii/S0888754302968527#SEC4 7 Rationale 7.1 Why Create a New URI Scheme for Identifiers from Public Namespaces? Under RFC 2718, "Guidelines for new URL Schemes" [RFC2718], it is stated that a URI scheme SHOULD have a "demonstrated utility", and in particular SHOULD be applied to "things that cannot be referred to in any other way". The "info" URI scheme allows identifiers within public namespaces, used for the identification of information assets, to be referred to within the URI allocation. Once a namespace is registered in the "info" Registry, the "info" URI scheme enables an information asset with an identifier in that namespace to be referenced by means of a URI. As a result, the information asset SHALL be considered a resource as defined in RFC 2396 [RFC2396] and SHALL enjoy the same common syntactic, semantic and shared language benefits that the URI presentation confers. 7.2 Why Not Use an existing URI Scheme for Identifiers from Public Namespaces? Existing URI schemes are not suitable for employment as the "info" URI scheme expressly disallows dereference. While examples of resource identifiers minted under other URI schemes may not always be dereferenceable, nevertheless there is a common expectation that such URIs can be dereferenced by various resolution mechanisms, whether they be location-dependent or location-independent resource identifiers. The "info" URI scheme applies to a class of resource identifiers which share a set of common properties including the property of non-dereference. 7.3 Why Not Create a New URN Namespace ID for Identifiers from Public Namespaces? RFC 2141 [RFC2141] states that "Uniform Resource Names (URNs) are intended to serve as persistent, location-independent, resource identifiers." The "info" URI scheme, on the other hand, asserts neither the persistence of the identifiers created under this scheme nor of the public namespaces grandfathered under this scheme. Rather Van de Sompel Expires - June 2004 [Page 11]
The "info" URI Scheme December 2003 it exists purely to disclose the identity of information assets and to facilitate a lightweight registration mechanism for public namespaces of identifiers managed according to the policies and business models of the Namespace Authorities. The "info" URI scheme is neutral with respect to identifier persistence. Moreover, for "info" to operate as a URN NID would require that "info" be constituted as a delegated naming authority. It is not clear that a URN NID would be an appropriate choice for naming authority delegation. Further, the "info" URI scheme is not dereferenceable in contrast to the specific recommendation given in RFC 1737, "Functional Requirements for Uniform Resource Names" [RFC1737] that "It is strongly recommended that there be a mapping between the names generated by each naming authority and URLs.". It would therefore be inappropriate to create a URN Namespace ID for the "info" namespaces. An extra consideration is that the "urn" URI syntax excludes hierarchy by reserving the slash "/" character. An "info" URI, on the other hand, admits of general hierarchy by allowing the slash "/" character (as well as more liberally allowing the ampersand "&" and tilde "~" characters) and therefore represents a lower barrier to entry in keeping with its intention of acting as a bridging mechanism to allow public namespaces to become part of the URI allocation. That is, an "info" URI is more widely supportive of "human transcribability" as discussed in RFC 2396 [RFC2396] than is a "urn" URI. Additionally the "urn" URI syntax does not support "fragment" components as does the "info" URI syntax for indirect identification of secondary resources. 8 Security Considerations The "info" URI scheme syntax is subject to the same security considerations as the generic URI syntax described in RFC 2396 [RFC2396]. An "info" URI is not dereferenceable and hence no resolution mechanisms are available to a URI processor. Therefore security considerations regarding the use of "info" URIs MUST be limited solely to the nature of the identifier string itself. 9 Acknowledgements The authors acknowledge the contributions of Michael Mealling, Verisign, and Patrick Hochstenbach, Los Alamos National Laboratory. Van de Sompel Expires - June 2004 [Page 12]
The "info" URI Scheme December 2003 10 Normative References [RFC2119] Bradner, S., "Key Words for Use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Retrieved September 20, 2003 from <http://www.ietf.org/rfc/rfc2119.txt>. [RFC2234] Crocker, D.H. and Overell, P., "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. Retrieved September 20, 2003 from <http://www.ietf.org/rfc/rfc2234.txt>. [RFC2279] Yergeau, F., "UTF-8, A Transformation Format for Unicode and ISO10646", RFC 2279, October 1996. Retrieved September 20, 2003 from <http://www.ietf.org/rfc/rfc2279.txt>. [RFC2396] Berners-Lee, T., R. Fielding and L. Manister, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998. Retrieved September 20, 2003 from <http://www.ietf.org/rfc/rfc2396.txt>. [RFC2718] Masinter, L., H. Alvestrand, D. Zigmond and P. Petke, "Guidelines for new URL Schemes", RFC 2718, November 1999. Retrieved September 20, 2003 from <http://www.ietf.org/rfc/rfc2718.txt>. [UNICODE] The Unicode Consortium. The Unicode Standard, Version 4.0.0, defined by: The Unicode Standard, Version 4.0 (Reading, MA, Addison-Wesley, 2003). ISBN 0-321-18578-1. 11 Non-Normative References [2396BIS] Berners-Lee, T., R. Fielding and L. Manister, "Uniform Resource Identifiers (URI): Generic Syntax", Internet- Draft (work in progress), June 2003. Retrieved November 25, 2003 from <http://www.ietf.org/internet-drafts/draft- fielding-uri-rfc2396bis-03.txt>. [BIBCODE] "NASA Astrophysics Data System Bibliographic Code". Retrieved August 1, 2003 from <http://adsdoc.harvard.edu/abs_doc/help_pages/data.html>. [DEWEY] "Dewey Decimal Classification". Retrieved September 20, 2003 from <http://www.oclc.org/dewey/>. [LCCN] "Library of Congress Control Number". Retrieved August 1, 2003 from <http://lcweb.loc.gov/marc/lccn_structure.html>. Van de Sompel Expires - June 2004 [Page 13]
The "info" URI Scheme December 2003 [NISO] National Information Standards Organization. Retrieved August 1, 2003 from <http://www.niso.org/>. [OCLCNUM] "Online Computer Library Center OCLC Control Number". Retrieved November 25, 2003 from <http://www.oclc.org/bibformats/en/fixedfield/oclc.shtm>. [OFI] Draft Standard for Trial Use ANSI/NISO Z39.88, "The OpenURL Framework for Context-Sensitive Services". Retrieved September 20, 2003 from <http://library.caltech.edu/openurl/Public_Comments.htm> [PII] "Publisher Item Identifier as a means of document identification". Retrieved September 25, 2003 from <http://www.elsevier.nl/inca/homepage/about/pii/>. [PMID] "PubMed Overview", National Library of Medicine. Retrieved September 25, 2003 from <http://www.ncbi.nlm.nih.gov/entrez/query/static/overview. html>. [SICI] ANSI/NISO Z39.56-1996 (R2002), "Serial Item and Contribution Identifier (SICI)", ISBN 1-880124-28-9. Retrieved September 25, 2003 from <http://www.niso.org/standards/resources/Z39-56-1996.pdf> 12 Authors' Addresses Herbert Van de Sompel Los Alamos National Laboratory, Research Library, MS-P362, PO Box 1663, Los Alamos, NM 87545-1362, USA <mailto:herbertv@lanl.gov> Tony Hammond Elsevier Ltd 32 Jamestown Road London, NW1 7BY, UK <mailto:t.hammond@elsevier.com> Eamonn Neylon Manifest Solutions Bicester Oxfordshire, OX26 2HX, UK <mailto:eneylon@manifestsolutions.com> Stuart L. Weibel OCLC Online Computer Library Center, Inc. Van de Sompel Expires - June 2004 [Page 14]
The "info" URI Scheme December 2003 6565 Frantz Road Dublin, OH 43017-3395, USA <mailto:weibel@oclc.org> 13 Full Copyright Statement Copyright (C) The Internet Society (2003). 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 copyrights defined in the Internet Standards process MUST be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Van de Sompel Expires - June 2004 [Page 15]
