Network Working Group J. Borbinha Request for Comments: XXXX National Library of Portugal Category: Informational August 2000 A URN Namespace for Resources Deposited in the National Library of Portugal 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 (2000). All Rights Reserved. Abstract This document proposes the "pt-bn" namespace. This namespace consists of the collections of resources deposited at the National Library of Portugal ("Biblioteca Nacional"), for immediate access or long-term preservation. In the moment of the editing of this document, the Portuguese Legal Deposit Law regulates the mandatory deposit in the National Library of Portugal of printed materials produced under the national jurisdiction, with the purpose to provide the public access the long-term preservation of the national scientific and cultural memory. With the definition of this URN namespace, the National Library intends to provide an on-line access to the bibliographic descriptions of the deposited resources, as also the on-line access to those with digital manifestations (when possible according their technical and legal requirements). This initiative is part of the development of a framework for the deposit of digital publications, to be promoted in a pro-active basis among the creators of these publications. Both the current URN framework and URN syntax support this namespace. 1. Introduction This document proposes the "pt-bn" namespace. This namespace consists of the collections of resources deposited at the National Library of Portugal ("Biblioteca Nacional"), for immediate access or long-term preservation. The namespace specification is for a formal namespace. 2. Specification Template Namespace ID: "pt-bn" requested. Registration Information: Registration version number: 1 Registration date: 2000-08-XX Declared registrant of the namespace: Jose Borbinha Jose.Borbinha@bn.pt National Library of Portugal Campo Grande, 83 1749-081 Lisbon - PORTUGAL Declaration of structure: The identifier has the following ABNF [2] specification: NSS = ndli-nss / isbn-nss / issn-nss / other-nss ndli-nss = "NDLI:" 1*DIGIT "-" 2 DIGIT isbn-nss = "ISBN:" isbn issn-nss = "ISSN:" issn [ ":" datetime ] other-nss = auth ":" string [ ":" datetime ] isbn = 10 (DIGIT / "-") DIGIT "-" (DIGIT / "X") issn = 4 DIGIT "-" 3 DIGIT (DIGIT / "X") datetime = year [ month [ day [ "-" time ] ] ] auth = string year = 4 DIGIT month = 2 DIGIT day = 2 DIGIT time = 1*(2 DIGIT) string = 1*(DIGIT / ALPHA / "-") "ndli" refers to the already defined and used national legal deposit number for printed material, which includes an integer number and the last two digits of the year. "issn" and "isbn" are, respectively, the International Standard Book Number and the International Standard Serial Number. "other-nss" refers to sub-namespaces to be assigned by the National Library for special authorities or collections of special genres of resources (a controlled list of these authorities will be maintained and published by the National Library). Dates and time are important to distinguish different issues of the same ISSN publication, as also for other possible genres cumulative in time. The format for the date is a profile of ISO 8601 (being accepted the formats YYYY, YYYYMM and YYYYMMDD). The format for time is a simplification of that standard, with the time expressed by any sequence of two digits, in the form HH, HHMM, HHMMSS, HHMMSSdd, etc., where "dd" can be any repeated sequence of decimal subdivisions of one second (useful for tiny time cumulative resources). Relevant ancillary documentation: Relevant documentation is found in the references [1], [2] and [3], detailed in the references' section of this document. Identifier uniqueness considerations: Each URN in the pn-bn namespace is unique, and never reused. National legal deposit numbers, ISSN numbers, and ISBN numbers have defined strict procedures for their assignments, assuring that uniqueness. The same care will be put by the National Library of Portugal in the assignment of sub-namespaces and numbers for these spaces. It must be referred, however, that by this schema a resource might have more than one URN, especially for those ones with national legal deposit numbers and also ISSN or ISSN numbers. This is not a drawback, but an interesting feature of the schema, made clear by the reference to the sub-namespace in the URN. Identifier persistence considerations: Persistence of the URNs of this namespace is independent of the mutability of the underlying resources. A URN once assigned will never be reassigned to a different resource; the assignment is persistent and immutable. The immutability of the resources is a requirement of the deposit policy (new versions of a document or publication will receive always a new URN, for instance). Process of identifier assignment: Resources deposited with already a ISSN, ISBN, or legal deposit number will have their URNs automatically generated according the rules of this schema. The assignment of new sub-namespaces will be a responsibility of the National Library of Portugal, according with rules to be yet defined by the institution. Process of identifier resolution: The resolution of URNs from the pt-bn space will be possible via HTTP, by a PURL service assured by the DNS "purl.pt". This service will be maintained by the National Library of Portugal, and will be able to resolve both URNs and PURLs, according the rule: PURL = "http://purl.pt/" ["urn:pt-bn:"] NSS The result of this resolution will be a URL for an "homepage" of the resource. For tangible resources (books, for example), the reference will be for the bibliographic record of that resource existing in the National Bibliographic Catalogue maintained by the PORBASE system. PORBASE is a collaborative structure, open to libraries with bibliographic resources relevant for the Portuguese science or culture (http://www.bn.pt/porbase). For digital resources, the reference will be also for its bibliographic record, which in this case might include a link to the contents. The National Library of Portugal will promote the distribution of the PURL resolution service among relevant ISPs - Internet Service Providers, namely by the assign of its DNS to several IPs, corresponding to servers in those ISPs with copies of the service. Rules for Lexical Equivalence: The entire URN is case-insensitive. Conformance with URN Syntax: There are no additional characters reserved. Validation mechanism: None additional to resolution specified Scope: Global. 3. Examples The following are examples of URNs that a resolver for this namespace can resolve: urn:pt-bn:isbn:972-21-0513-2 urn:pt-bn:issn:0870-273X urn:pt-bn:issn:0870-5968:20000801 urn:pt-bn:dli:42789-91 The resolution service "purl.pt" will be able to recognize both the following URNs and PURLs for these identifiers: http://purl.pt/urn:pt-bn:isbn:972-21-0513-2 http://purl.pt/urn:pt-bn:issn:0870-273X http://purl.pt/urn:pt-bn:issn:0870-5968:20000801 http://purl.pt/urn:pt-bn:ndli:42789-91 http://purl.pt/isbn:972-21-0513-2 http://purl.pt/issn:0870-273X http://purl.pt/issn:0870-5968:20000801 http://purl.pt/ndli:42789-91 4. Security Considerations Because this namespace defines no additional reserved characters, it does not add any security considerations beyond those inherent from the existence of the reserved characters from [1]. Further, none of the reserved characters from [1] are used in the definition of the NSS. This means that resolvers for this namespace may be considered "secure" in the sense that any escaping of characters in the NSS MUST result in the resolver indicating that the URN has incorrect syntax. 5. Acknowledgments Thanks to Ryan Moats, for his example in [4], from which this document got precious inspiration. 6. References Request For Comments (RFC) and Internet Draft documents are available from numerous mirror sites. [1] Moats, R., "URN Syntax", RFC 2141, May 1997. [2] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. [3] Daigle, L., van Gulik, D., Ianella, R., Faltstrom, P., "URN Namespace Definition Mechanisms", RFC 2611, June 1999 [4] Moats, R., "A URN Namespace for IETF Documents", RFC2648, August 1999. 7. Author's Address Jose Borbinha National Library of Portugal Campo Grande, 83 1749-081 Lisbon PORTUGAL EMail: Jose.Borbinha@bn.pt 8. Full Copyright Statement Copyright (C) The Internet Society (1999). 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