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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group J. Hakala 3 Internet-Draft The National Library of Finland 4 Obsoletes: 3188 (if approved) April 16, 2018 5 Intended status: Informational 6 Expires: October 18, 2018 8 Using National Bibliography Numbers as Uniform Resource Names 9 draft-hakala-urn-nbn-rfc3188bis-00 11 Abstract 13 National Bibliography Numbers, NBNs, are used by the national 14 libraries and other organizations in order to identify resources in 15 their collections. Generally, NBNs are applied to resources that are 16 not catered for by established (standard) identifier systems such as 17 ISBN. 19 A URN (Uniform Resource Names) namespace for NBNs was established in 20 2001 in RFC 3188. Since then, several European national libraries 21 have implemented URN:NBN-based systems. 23 This document replaces RFC 3188 and defines how NBNs can be supported 24 within the updated URN framework. A revised namespace registration 25 (version 4) compliant to RFC 8141 is included. 27 Relationship to earlier documents 29 This draft replaces draft-ietf-urnbis-rfc3188bis-nbn-urn-04, posted 30 2012-10-22. 32 Status of This Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at https://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on October 18, 2018. 49 Copyright Notice 51 Copyright (c) 2018 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 This document is subject to BCP 78 and the IETF Trust's Legal 55 Provisions Relating to IETF Documents 56 (https://trustee.ietf.org/license-info) in effect on the date of 57 publication of this document. Please review these documents 58 carefully, as they describe your rights and restrictions with respect 59 to this document. Code Components extracted from this document must 60 include Simplified BSD License text as described in Section 4.e of 61 the Trust Legal Provisions and are provided without warranty as 62 described in the Simplified BSD License. 64 Table of Contents 66 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 67 1.1. Discussion list . . . . . . . . . . . . . . . . . . . . . 4 68 2. Conventions used in this document . . . . . . . . . . . . . . 4 69 3. Fundamental Namespace and Community Considerations for NBN . 5 70 3.1. The URN:NBN Namespace . . . . . . . . . . . . . . . . . . 5 71 3.2. Community Considerations for NBNs . . . . . . . . . . . . 5 72 4. National Bibliography Numbers (NBNs) . . . . . . . . . . . . 7 73 4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 7 74 4.2. Encoding Considerations and Lexical Equivalence . . . . . 7 75 4.3. Resolution and Persistence of NBN-based URNs . . . . . . 9 76 4.4. Additional considerations . . . . . . . . . . . . . . . . 10 77 5. URN Namespace ID (NID) Registration for the National 78 Bibliography Number (NBN) . . . . . . . . . . . . . . . . . . 10 79 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 80 7. Security Considerations . . . . . . . . . . . . . . . . . . . 15 81 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16 82 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 16 83 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 84 10.1. Normative References . . . . . . . . . . . . . . . . . . 16 85 10.2. Informative References . . . . . . . . . . . . . . . . . 17 86 Appendix A. Significant Changes from RFC 3188 . . . . . . . . . 18 87 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 19 88 B.1. draft-hakala-rfc3188bis-nbn-urn-00 to draft-ietf- 89 urnbis-*-00 . . . . . . . . . . . . . . . . . . . . . . . 19 90 B.2. draft-ietf-urnbis-rfc3188bis-nbn-urn-00 to -01 . . . . . 20 91 B.3. draft-ietf-urnbis-rfc3188bis-nbn-urn-01 to -02 . . . . . 20 92 B.4. draft-ietf-urnbis-rfc3188bis-nbn-urn-02 to -03 . . . . . 20 93 B.5. draft-ietf-urnbis-rfc3188bis-nbn-urn-03 to -04 . . . . . 21 94 B.6. draft-ietf-urnbis-rfc3188bis-nbn-urn-04 (2012-10-22) to 95 draft-hakala-urn-nbn-rfc3188bis-00 . . . . . . . . . . . 21 96 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 21 98 1. Introduction 100 One of the basic permanent URI schemes (cf. RFC 3986 [RFC3986], 101 [IANA-URI]) is 'URN' (Uniform Resource Name) as originally defined in 102 RFC 2141 [RFC2141] with new definitions and registration procedure in 103 2017 [RFC8141]. Any traditional identifier, when used within the URN 104 system, must to have a namespace of its own, registered with IANA 105 [IANA-URN]. National Bibliography Number (NBN) is one such 106 namespace, specified in 2001 in RFC 3188 [RFC3188]. 108 URN:NBNs are in production use in several European countries 109 including (in alphabetical order) Austria, Finland, Germany, Italy, 110 Hungary, the Netherlands, Norway, Sweden, and Switzerland. The 111 URN:NBN namespace is collectively managed by these national 112 libraries. URN: NBNs have been applied to diverse content including 113 Web archives, digitized materials, research data, and doctoral 114 dissertations. They can be used by the national libraries and 115 organizations co-operating with them. 117 As a part of the initial development of the URN system in the late 118 1990s, the IETF URN working group agreed that it was important to 119 demonstrate that the URN syntax can accommodate existing identifier 120 systems. RFC 2288 [RFC2288] investigated the feasibility of using 121 ISBN, ISSN and SICI (see below) as URNs, with positive results; 122 however, it did not formally register corresponding URN namespaces. 123 This was in part due to the still evolving process to formalize 124 criteria for namespace definition documents and registration, 125 consolidated later in the IETF, first into RFC 2611 [RFC2611], then 126 into RFC 3406 [RFC3406], and now given by RFC 8141 [RFC8141]. 128 URN Namespaces have subsequently been registered for NBN (National 129 Bibliography Number), ISBN (International Standard Book Number), and 130 ISSN (International Serial Standard Number) in RFCs 3188 [RFC3188], 131 3187 [RFC3187], and 3044 [RFC3044], respectively. 133 The term "National Bibliography Number" encompasses persistent local 134 identifier systems that the national libraries and their partner 135 organizations use in addition to the more formally (and 136 internationally) established identifiers. These partner 137 organizations include university libraries, universities and other 138 research organizations and governmental organizations. Some national 139 libraries have a lot of these liaisons; for instance, the German 140 National Library had almost 400 by early 2018 [NBN-Resolving]. 142 In practice, NBN differs from standard identifier systems such as 143 ISBN and ISSN because it is not a single identifier system with 144 standard-specified scope and syntax. Each NBN implementer creates 145 its own system with its own syntax and assignment rules. Each user 146 organization is also obliged to keep track of how NBNs are being 147 used, but within the generic framework set in this document, local 148 NBN assignment policies may vary considerably. 150 Historically, NBNs were only applied in the national bibliographies 151 to identify the resources catalogued into it. Prior to the emergence 152 of bibliographic standard identifiers identifiers in the early 1970s, 153 every publication got an NBN. 155 Since the late 1990s, the NBN scope has been extended to cover a vast 156 range of digitized and born digital resources. Only a small subset 157 of these resources is cataloged in the national bibliographies or 158 other bibliographic databases. Digitized resources and their 159 component parts (such as still images in books, or journal articles) 160 are examples of resources that may get NBNs. 162 It is possible to extend the scope of the NBN much further. The 163 National Library of Finland is using them in the Finnish National 164 Ontology Service Finto to identify corporate names (see 165 http://finto.fi/cn/en/). NBNs to identify metadata elements provides 166 a stable basis for creation of linked data. 168 Simple guidelines for using NBNs as URNs and the original namespace 169 registration were published in RFC 3188 [RFC3188]. The RFC at hand 170 replaces RFC 3188; sections discussing the methods in which URN:NBNs 171 should be resolved have been updated, unused features have been 172 eliminated, and the text is compliant with the stipulations of the 173 revised URN specification [RFC8141]. 175 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 176 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 177 document are to be interpreted as described in RFC 2119 [RFC2119]. 179 1.1. Discussion list 181 Comments are welcome and should be directed to the urn@ietf.org 182 mailing list or the authors. 184 [[CREF1: RFC-Editor: this subsection to be deleted before RFC 185 publication.]] 187 2. Conventions used in this document 189 "NBN" refers to any National Bibliography Number identifier system 190 used by the national libraries and other institutions, which use 191 these identifiers with the national library's support and permission. 193 In this memo, "URN:NBN" is used as a shorthand for "NBN-based URN". 195 3. Fundamental Namespace and Community Considerations for NBN 197 3.1. The URN:NBN Namespace 199 NBNs are widely used to identify both hand-held and digital resources 200 in the collections of national libraries and other institutions that 201 are responsible for preserving the cultural heritage of their 202 constituents. Resources in these collections are usually preserved 203 for a long time (i.e., for centuries). While the preferred methods 204 for digital preservation may vary over time and depending on the 205 content, the favorite one is currently migration. Whenever 206 necessary, a resource in outdated file format is migrated into a more 207 modern file format. All old versions of the resource are also kept, 208 in order to alleviate the negative effects of partially successful 209 migrations and gradual loss of original look and feel that may 210 accompany even fully successful migrations. When there are multiple 211 manifestations of a digital object, each one SHOULD have its own NBN. 213 NBNs SHOULD only be used for objects when standard identifiers such 214 as ISBN are not applicable. However, NBNs MAY be used for component 215 resources even when the resource as a whole qualifies for a standard 216 identifier. For instance, even if a digitized book has an ISBN, JPEG 217 image files of its pages get NBNs. These URN:NBNs can be used as 218 persistent links to the pages. 220 The scope of standard identifier systems such as ISBN and ISSN is 221 limited; they are applicable only to certain kinds of resources. 222 Generally speaking, the role of the NBN is to fill in the gaps. 223 Collectively, the standard identifiers and NBNs cover all resources 224 the national libraries and their partners need to preserve for the 225 long term. 227 Section 4 below, and there in particular Section 4.1, presents a more 228 detailed overview of the structure of the NBN namespace, related 229 institutions, and the identifier assignment principles used. 231 3.2. Community Considerations for NBNs 233 National libraries are the key organizations providing persistent URN 234 resolution services for resources identified with NBNs, independent 235 of their form. National libraries MAY allow other organizations such 236 as university libraries or governmental organizations to assign NBNs 237 to the resources they preserve for long term. In such case, the 238 national library MUST co-ordinate the use of NBNs at the national 239 level. National libraries can also provide URN resolution services 240 and technical services to other NBN users. These organizations MUST 241 either establish their own URN resolution services or use the 242 technical infrastructure provided by the national library. In the 243 URN:NBN namespace, each persistent identifier should be resolvable 244 and provide one or more resolution services. 246 NBNs MAY be used to identify component resources, but the NBN 247 Namespace does not specify a generic, intrinsic syntax for doing 248 that. However, there are at least three different ways in which 249 component resources can be identified and used within the NBN 250 namespace. 252 The simplest and probably the most common approach is to assign a 253 separate NBN for each component resource such as a file containing a 254 digitized page of a book, and make no provisions to make such NBNs 255 discernible in a systematical way from others. The URN:NBN assigned 256 to the component resource enables direct and persistent access to the 257 page, which might otherwise be available only via browsing the book 258 from the title page to the page wanted. 260 Second, a local "fragment" syntax MAY be used to identify component 261 resources in a structured manner within the NSS, independently of the 262 requirements of RFC 3986. These private fragment identifiers SHOULD 263 be recognized as such by the appropriate URN resolver application. 264 The resolver SHOULD be able to process the fragment part in the URN: 265 NBN correctly; if so, the result is the identified component part of 266 the resource. For instance, if the resource is a database table, the 267 identified component could be a single data element stored in the 268 table. 270 Finally, if the stipulations of the URI Generic Syntax [RFC3986] and 271 the Internet media type specification [RFC2046] are met, in 272 accordance with the provisions in RFC 8141, the URN f-component MAY 273 be attached to URN:NBNs in order to indicate the desired location 274 within the resource supplied by URN resolution. 276 Note that the f-component is not a part of the NSS and therefore the 277 component part is not identified. Moreover, the resolution process 278 SHALL retrieve the entire resource. The fragment selection is 279 applied by the resolution client (e.g., browser) to the media 280 returned by the resolution process. In other words, in this latter 281 case the fragments are logical and physical components of the 282 identified resource whereas in the former cases these "fragments" are 283 actually complete, independently named entities. 285 Resources identified by NBNs are not always available in the 286 Internet. In that case, a surrogate such as a metadata record of the 287 identified resource can be supplied. 289 If an NBN identifies an immaterial work, descriptive metadata about 290 the work SHOULD be supplied. The metadata record MAY contain links 291 to Internet-accessible digital manifestations of the work. 293 Section 4 below, and in particular Section 4.3 therein, presents a 294 detailed overview of the application of the URN:NBN Namespace as well 295 as the principles of, and systems used for, the resolution of NBN- 296 based URNs. 298 4. National Bibliography Numbers (NBNs) 300 4.1. Overview 302 National Bibliography Number (NBN) is a generic term referring to a 303 group of identifier systems administered by the national libraries 304 and institutions authorized by them. The NBN assignment is typically 305 performed by the organization hosting the resource. National 306 libraries are committed to permanent preservation of their deposit 307 collections. 309 Each national library uses NBNs independently of other national 310 libraries; apart from this document, there is no global authority 311 that specifies or controls NBN usage. NBNs as such are unique only 312 on the national level. When used as URNs, base NBN strings MUST be 313 augmented with a controlled prefix, which is the particular nation's 314 ISO 3166-1 alpha-2 two-letter country code. These prefixes guarantee 315 uniqueness of the URN:NBNs at the global scale [Iso3166MA"/>. 317 A national library using URN:NBNs SHOULD specify a local assignment 318 policy; such policy SHOULD limit the URN:NBN usage to the information 319 resources stored permanently in the national library's digital 320 collections or databases. A more liberal URN:NBN assignment policy 321 MAY be applied, but NBNs assigned to a short-lived resources SHOULD 322 NOT be made URN: NBNs. 324 URN:NBN assignment policy SHOULD also clarify the local policy 325 concerning identifier assignment to component parts of resources, and 326 specify with sufficient detail the syntax of local component 327 identifiers (if there is one as a discernible part of the NBNs). The 328 policy SHOULD also cover any employed extensions to the default NBN 329 scope (e.g., to cover identification of metadata elements). 331 4.2. Encoding Considerations and Lexical Equivalence 333 Expressing NBNs as URNs is usually straightforward, as traditionally 334 only ASCII characters have been used in NBN strings. If necessary, 335 NBNs must be translated into canonical form as specified in RFC 8141. 337 When an NBN is used as a URN, the namespace-specific string (NSS) 338 MUST consist of three parts: 340 o a prefix, structured as a primary prefix, which is a two-letter 341 ISO 3166-1 country code, and zero or more secondary prefixes, each 342 indicated by a delimiting colon character (:) and a sub-namespace 343 identifier, 345 o a hyphen (-) as a delimiting character, and 347 o the NBN string. 349 The prefix is case-insensitive. An NBN string can be either case- 350 sensitive or case-insensitive, depending on the NBN syntax applied. 351 Future implementers of NBNs SHOULD make their NBN strings case- 352 insensitive. 354 Different delimiting characters are not semantically equivalent. 356 Use of colon as the delimiting character is allowed if and only if 357 the country code-based NBN namespace (identified by the respective 358 ISO 3166-1 country code used as the primary part of the prefix) is 359 split further into smaller sub-namespaces, in which case the colon 360 separates the ISO 3166-1 country code from the sub-namespace 361 identifier. These subdivisions (including the colon separator) form 362 an optional part of the prefix. A colon MUST NOT be used for any 363 other purpose in the prefix. 365 A hyphen MUST be used for separating the prefix and the NBN string, 366 or the part of the NBN string that is assigned to the identified 367 object by a sub-division authority. 369 If there are several national libraries in one country, these 370 libraries MUST agree on how to divide the national namespace between 371 themselves using this method before the URN:NBN assignment begins in 372 any of these libraries. 374 A national library MAY also assign to trusted organization(s) -- such 375 as a university or a government institution -- its own NBN sub- 376 namespace. The sub-namespace MAY be further divided by the partner 377 organization (the national library MUST be informed about these sub- 378 namespaces). 380 Being part of the prefix, sub-namespace identifier strings are case- 381 insensitive. They MUST NOT contain any hyphens. 383 The sub-namespace identifiers used beneath a country-code-based 384 namespace MUST be registered on the national level by the national 385 library that assigned the code. The national register of these codes 386 SHOULD be made available online. 388 Models (indicated linebreak inserted for readability): 390 URN:NBN:- 392 URN:NBN::-\ 393 395 Examples: 397 URN:NBN:fi-fe201003181510 399 urn:nbn:ch:bel-9039 401 urn:nbn:se:uu:diva-3475 403 urn:nbn:hu-3006 405 4.3. Resolution and Persistence of NBN-based URNs 407 Eventually, URNs might be resolved with the help of a resolver 408 discovery service (RDS). Since no such system has been installed yet 409 in the Internet, URN:NBNs are usually embedded in HTTP URIs in order 410 to make them actionable in the present Internet. In these HTTP URIs, 411 the authority part must point to the appropriate URN resolution 412 service. For instance, in Finland, the address of the national URN 413 resolver is . Thus the HTTP URI for the Finnish URN 414 in the example above is . 416 The country code-based prefix part of the URN:NBN namespace-specific 417 string will provide a hint needed to find the correct resolution 418 service for URN:NBNs from the global resolver discovery service when 419 it is established. 421 There are three inter-related aspects of persistence that need to be 422 discussed: persistence of the objects itself, persistence of the 423 identifier, and persistence of the URN resolvers. 425 NBNs have traditionally been assigned to printed resources, which 426 tend to be persistent. In contrast, digital resources require 427 frequent migrations to guarantee accessibility. Although it is 428 impossible to estimate how often migrations are needed, hardware and 429 software upgrades take place frequently, and a life time exceeding 430 10-20 years can be considered as long. 432 However, it is a common practice to keep also the original and 433 previously migrated versions of resources. Therefore even outdated 434 versions of resources can be available, no matter how old or 435 difficult to use they have become. 437 If all versions of a resource are kept, a user who requires 438 authenticity may retrieve the original version of the resource, 439 whereas a user to whom the ease of use is a priority is likely to be 440 satisfied with the latest version. In order to enable the users to 441 find the best match, an archive can link all manifestations of a 442 resource to each other (possibly via a work level metadata record) so 443 as to make the users aware of them. 445 Thus, even if specific versions of digital resources are not normally 446 persistent, persistent identifiers such as URN:NBNs support 447 information architectures that enable persistent access to any 448 version of the resource, including ones which can only be utilized by 449 using digital archeology tools such as custom made applications to 450 render the resource. 452 Persistence of URN resolvers themselves is mainly an organizational 453 issue, related to the persistence of organizations maintaining them. 454 As URN:NBN resolution services will be supplied (primarily) by the 455 national libraries, these services are likely to be long-lived. 457 4.4. Additional considerations 459 URN:NBNs (or other persistent identifiers) SHOULD be applied to all 460 resources which have been prioritized in the organization's digital 461 preservation plan. 463 URN:NBNs SHOULD NOT be assigned to resources that are known to not be 464 persistent. URN:NBNs MAY however be applied to resources that have a 465 low-level preservation priority and will not be migrated to more 466 modern file formats. 468 If the identified version of a resource has disappeared, the 469 resolution process SHOULD supply a surrogate if one exists, such as 470 the original printed version of a resource, or a more modern digital 471 version of that resource. 473 5. URN Namespace ID (NID) Registration for the National Bibliography 474 Number (NBN) 476 This URN Namespace registration describes how National Bibliography 477 Numbers (NBNs) can be supported within the URN framework; it uses the 478 updated IANA template specified in RFC 8141. 480 Namespace ID: NBN 481 This Namespace ID was formally assigned to the National 482 Bibliography Number in October 2001 when the namespace was 483 registered officially [RFC3188]. Utilization of URN:NBNs had 484 started in demo systems already in 1998. Since 2001, tens of 485 millions of URN:NBNs have been assigned. The number of users of 486 the namespace has grown in two ways: new national libraries have 487 started using NBNs, and many national libraries using the system 488 have formed new liaisons. 490 Kind of named resources: 491 Resources (digital or otherwise) in the collections of national 492 libraries and their partner organizations. 493 Component parts of identified resources. 494 Metadata records describing the identified resources. 495 Individual data elements in identified metadata records. 497 Registration Information: 498 Version: 4 499 Date: 2018-04-09 501 Declared registrant of the namespace: 502 Name: Juha Hakala 503 Affiliation: Senior Adviser, The National Library of Finland 504 Email: juha.hakala@helsinki.fi 505 Postal: P.O.Box 15, 00014 Helsinki University, Finland 506 Web URL: http://www.nationallibrary.fi/ 508 The National Library of Finland registered the namespace on behalf 509 of the Conference of the European National Librarians (CENL) and 510 Conference of Directors of National Libraries (CDNL). The NBN 511 namespace is available for free for the national libraries. They 512 MAY allow other organizations to assign URN:NBNs and use the 513 resolution services established by the library for free or for a 514 fee. The fees, if collected, SHOULD be based on, e.g., the 515 maintenance costs of the system. 517 Declaration of syntactic structure of NSS part: 518 The namespace-specific string (NSS) will consist of three parts: 520 * a prefix, consisting of an ISO 3166-1 alpha-2 country code and 521 optional sub-namespace code(s) separated by colon(s), 523 * a hyphen (-) as the delimiting character, and 525 * an NBN string assigned by the national library or sub-delegated 526 authority. 528 Formal declaration of the NSS: 529 This definition uses ABNF [RFC5234]. 531 nbn_nss = prefix "-" nbn_string 533 prefix = iso_cc *( ":" subspc ) 534 ; the entire prefix is case-insensitive 536 iso_cc = 2ALPHA 537 ; country code as assigned by ISO 3166, part 1 -- 538 ; identifies the national library 539 ; to which the branch is delegated 541 subspc = 1*(ALPHA / DIGIT) 542 ; as assigned by the respective national library 544 nbn_string = <specific per prefix> 545 ; MUST adhere to RFC 3986 <path-rootless> syntax; 546 ; parsers must regard nbn_strings as case-sensitive 548 Colon MAY be used as a delimiting character only within the 549 prefix, between ISO 3166-1 country code and sub-namespace code(s), 550 which split the national namespace into smaller parts. 552 Whereas the prefix is regarded as case-insensitive, NBN-strings 553 MAY be case-sensitive at the preference of the assigning 554 authority; parsers therefore MUST treat these as case-sensitive; 555 any case mapping needed to introduce case-insensitivity MUST be 556 implemented in the responsible resolution system. 558 Hyphen MUST be used as the delimiting character between the prefix 559 and the NBN string. Within the NBN string, hyphen MAY be used for 560 separating different sections of the identifier from one another. 562 All two-letter codes are reserved by the ISO 3166 Maintenance 563 Agency for either existing and possible future ISO country codes 564 (or for private use). 566 Sub-namespace identifiers MUST be registered on the national level 567 by the national library that assigned the code. The list of such 568 identifiers SHOULD be available via the Web. 570 See Section 4.2 of RFC XXXX for examples. 572 Relevant ancillary documentation: 574 National Bibliography Number (NBN) is a generic name referring to 575 a group of identifier systems used by the national libraries and 576 their partner organizations for identification of resources (and 577 their component parts) that lack a 'canonical' identifier. The 578 scope of NBN has been extended to also include, e.g., metadata 579 records and their elements. Each national library uses NBNs 580 independently of other national libraries; there is neither a 581 general standard defining the NBN syntax nor a global authority to 582 control the use of these identifier systems. 584 The syntax of NBN strings is specified locally. NBNs used in 585 national bibliographies contain only characters that belong to the 586 US-ASCII character set. Following the expansion of the NBN scope 587 and semi- and fully automated NBN assignment processes, some 588 future NBNs MAY contain characters that MUST be translated into 589 canonical form according to the specifications in RFC 8141. 591 Conformance with URN syntax: 592 The NSS syntax specified in this registration is in full 593 conformance with RFC 8141 and its predecessors. 595 Rules for lexical equivalence of NSS part: 596 The prefix, consisting of an ISO 3166-1 country code and its 597 (optional) sub-divisions, is case-insensitive. The NBN string MAY 598 be case-sensitive or case-insensitive, depending on the rules 599 chosen by the NBN authority designated by the prefix; therefore, 600 general-purpose resolver clients without sub-namespace specific 601 knowledge) MUST treat NBN strings as case-sensitive. Syntax 602 requirements expressed in RFC 8141 MUST be taken into account. 604 Formally, two URN:NBNs are lexically equivalent if they are octet- 605 by-octet equal after the following (conceptional) preprocessing: 607 1. normalize the case of the leading "urn:" token; 609 2. normalize the case of the prefix (country code and its 610 optional sub-divisions); 612 3. normalize the case of any percent-encoding; 614 Note: The case used in the normalization steps is a local matter; 615 implementations can normalize to lower or upper case as they see 616 fit, they only need to do it consistently. 618 Usage of r-component and q-component: 619 URN:NBN resolvers MAY support several services. Some of them have 620 been formally specified in RFC 2483; some remain unspecified. 622 Examples of existing relevant services are URI to URL or URLs, URI 623 to URN or URNs, URI to resource or resources, and URI to resource 624 metadata. In the latter case it is important to be able to 625 indicate the preferred metadata format or the completeness of the 626 metadata record or the metadata content requested such as table of 627 contents. A URN resolver maintained by a national library can 628 utilize for instance the national bibliography, digital asset 629 management systems and digital preservation systems to supply 630 these services. 632 Examples of services that can be specified and implemented in the 633 future: request the oldest and most original version of the 634 resource; request the latest version of the resource, and request 635 rights metadata related to the resource. 637 Depending on the technical infrastructure within which digital 638 resources are preserved and made available, any service can be 639 provided either via q-component, r-component or both. 641 Usage of f-component: 642 If URI-to-resource service is used and the media type of a 643 resource supports the use of an f-component, it can be used to 644 indicate a location within the identified resource because NBNs 645 SHOULD be assigned to one and only one version of a resource, such 646 as a PDF version of an article. 648 The URN:NBN Namespace does not impose any restrictions of its own 649 on f-component usage. 651 Identifier uniqueness and persistence considerations: 652 NBNs as such are not unique; different national libraries can 653 assign the same NBN to different resources. Therefore, to 654 guarantee the uniqueness of URN:NBNs, a prefix, based on the ISO 655 country code, is added to the resource. An NBN, once it has been 656 assigned to a resource, MUST be persistent, and therefore URN:NBNs 657 are persistent as well. 659 A URN:NBN, once it has been generated from a NBN, MUST NOT be re- 660 used for another resource. 662 Users of the URN:NBN namespace MUST ensure that they do not assign 663 the same URN:NBN twice. Different policies can be applied to 664 guarantee this. For instance, NBNs and corresponding URN:NBNs MAY 665 be assigned sequentially by programs in order to avoid human 666 mistakes. It is also possible to use printable representations of 667 checksums such as SHA-1 [RFC6234] or MD5 [RFC1321] as NBNs. 669 Process of identifier assignment: 671 Assignment of NBN-based URNs MUST be controlled on national level 672 by the national library (or national libraries, if there is more 673 than one). National guidelines MAY differ, but the identified 674 resources themselves SHOULD be persistent. 676 Different URN:NBN assignment policies have resulted in varying 677 levels of control of the assignment process. Manual URN 678 assignment by the library personnel provides the tightest control, 679 especially if the URN:NBNs cover only resources catalogued into 680 the national bibliography. In most national libraries, the scope 681 of URN:NBN is already much broader than this. Usage rules MAY 682 vary within one country, from one URN:NBN sub-namespace to the 683 next. As of yet, there are no international guidelines for 684 URN:NBN use beyond those expressed in this document. 686 Process for identifier resolution: 687 See Section 4.3 of RFC XXXX. 689 Validation mechanism: 690 None specified on the global level (beyond a routine check of 691 those characters that require special encoding when employed in 692 URIs). NBNs may have a well specified and rich syntax (including, 693 e.g., fixed length and checksum). In such case, it is possible to 694 validate the correctness of NBNs programmatically. 696 Scope: 697 NBNs are applied to resources held in the collections of national 698 libraries and their partner organizations. NBNs may also be used 699 to identify, e.g., component parts of these resources or metadata 700 records describing resources or their component parts. 702 6. IANA Considerations 704 IANA is asked to update the existing registration of the Formal URN 705 Namespace 'NBN' using the template given above in Section 5. 707 7. Security Considerations 709 This document proposes means of encoding NBNs as URNs. A URN 710 resolution service for NBN-based URNs is depicted, but only at a 711 generic level; thus, questions of secure or authenticated resolution 712 mechanisms and authentication of users are out of scope of this 713 document. It does not deal with means of validating the integrity or 714 authenticating the source or provenance of URN:NBNs. Issues 715 regarding intellectual property rights associated with objects 716 identified by the URN:NBNs are also beyond the scope of this 717 document, as are questions about rights to the databases that might 718 be used to construct resolution services. 720 Beyond the generic security considerations laid out in the underlying 721 documents listed in the Normative References (Section 9.1), no 722 specific security threats have been identified for NBN-based URNs. 724 8. Acknowledgements 726 Revision of RFC 3188 started during the project PersID [PERSID] Later 727 the revision was included in the charter of the URNbis working group 728 and worked on in that group in parallel with what became RFC 8141 and 729 RFC 8254. The author wishes to thank his colleagues in the PersID 730 project and the URNbis participants for their support and review 731 comments. 733 Tommi Jauhiainen has provided feedback on an early version of this 734 draft. The author wishes to thank Tommi Jauhiainen, Bengt Neiss, and 735 Lars Svensson for the comments they have provided to various versions 736 of this draft. 738 John Klensin provided significant editorial and advisory support for 739 late versions of the draft. 741 9. Contributors 743 Alfred Hoenes was the editor and co-author of two of the documents 744 from which this one is, in part, derived. This document would not 745 have been possible without his contributions. 747 10. References 749 10.1. Normative References 751 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 752 Requirement Levels", BCP 14, RFC 2119, 753 DOI 10.17487/RFC2119, March 1997, 754 . 756 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 757 Resource Identifier (URI): Generic Syntax", STD 66, 758 RFC 3986, DOI 10.17487/RFC3986, January 2005, 759 . 761 [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 762 Specifications: ABNF", STD 68, RFC 5234, 763 DOI 10.17487/RFC5234, January 2008, 764 . 766 [RFC8141] Saint-Andre, P. and J. Klensin, "Uniform Resource Names 767 (URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017, 768 . 770 10.2. Informative References 772 [I-D.ietf-urnbis-rfc3187bis-isbn-urn] 773 Huttunen, M., Hakala, J., and A. Hoenes, "Using 774 International Standard Book Numbers as Uniform Resource 775 Names", October 2006. 777 draft-ietf-urnbis-rfc3187bis-isbn-urn-03 (Expired draft). 779 [IANA-URI] 780 IANA, "URI Schemes Registry", 781 . 783 [IANA-URN] 784 IANA, "URN Namespace Registry", 785 . 787 [Iso3166MA] 788 ISO, "ISO Maintenance agency for ISO 3166 country codes", 789 2006, . 791 [NBN-Resolving] 792 Deutsche Nationalbibliothek, "URN:NBN Resolver fuer 793 Deutschland und Schweiz: Information ueber Partner 794 Institutionen", Captured 2018-04-09, 795 . 797 [PERSID] PersID initiative, 2009-2011, "persid: Building a 798 persistent identifier infrastructure", 799 Captured 2018-04-09, . 801 [RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321, 802 DOI 10.17487/RFC1321, April 1992, 803 . 805 [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail 806 Extensions (MIME) Part Two: Media Types", RFC 2046, 807 DOI 10.17487/RFC2046, November 1996, 808 . 810 [RFC2141] Moats, R., "URN Syntax", RFC 2141, DOI 10.17487/RFC2141, 811 May 1997, . 813 [RFC2288] Lynch, C., Preston, C., and R. Daniel, "Using Existing 814 Bibliographic Identifiers as Uniform Resource Names", 815 RFC 2288, DOI 10.17487/RFC2288, February 1998, 816 . 818 [RFC2611] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom, 819 "URN Namespace Definition Mechanisms", BCP 33, RFC 2611, 820 DOI 10.17487/RFC2611, June 1999, 821 . 823 [RFC3044] Rozenfeld, S., "Using The ISSN (International Serial 824 Standard Number) as URN (Uniform Resource Names) within an 825 ISSN-URN Namespace", RFC 3044, DOI 10.17487/RFC3044, 826 January 2001, . 828 [RFC3187] Hakala, J. and H. Walravens, "Using International Standard 829 Book Numbers as Uniform Resource Names", RFC 3187, 830 DOI 10.17487/RFC3187, October 2001, 831 . 833 [RFC3188] Hakala, J., "Using National Bibliography Numbers as 834 Uniform Resource Names", RFC 3188, DOI 10.17487/RFC3188, 835 October 2001, . 837 [RFC3406] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom, 838 "Uniform Resource Names (URN) Namespace Definition 839 Mechanisms", RFC 3406, DOI 10.17487/RFC3406, October 2002, 840 . 842 [RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms 843 (SHA and SHA-based HMAC and HKDF)", RFC 6234, 844 DOI 10.17487/RFC6234, May 2011, 845 . 847 [RFC8254] Klensin, J. and J. Hakala, "Uniform Resource Name (URN) 848 Namespace Registration Transition", RFC 8254, 849 DOI 10.17487/RFC8254, October 2017, 850 . 852 Appendix A. Significant Changes from RFC 3188 854 Numerous clarifications based on a decade of experience with RFC 855 3188. 857 Non-ISO 3166 (country code) based NBNs have been removed due to lack 858 of usage. 860 In accordance with established practice, the whole NBN prefix is now 861 declared case-insensitive. 863 Updated URN:NBN Namespace Registration template for IANA; whole 864 document adapted to new URN Syntax document, RFC 2141bis, and new URN 865 Namespace Registration document, RFC 3406bis (now retired and merged 866 into 2141bis. 868 Use of query directives and fragment parts with this Namespace is now 869 specified, in accordance with the aforementioned RFCs. 871 Appendix B. Change Log 873 [[CREF2: RFC-Editor: Please delete this whole section before RFC 874 publication.]] 876 B.1. draft-hakala-rfc3188bis-nbn-urn-00 to draft-ietf-urnbis-*-00 878 o formal updates for a WG draft; no more "Updates: 2288"; 880 o introduced references to other URNbis WG documents; 882 o changes based on review by Tommi Jauhiainen; 884 o Sect. 3 restructured into namespace and community considerations; 886 o old Sect. 7 incorporated in new Sect. 3.1; 888 o Security Considerations: old Section 4.5 merged into Section 5; 890 o added guidelines for when two manifestations of the same work 891 should get different URN:NBNs; 893 o clarified role of ISO 3166/MA for ISO 3166-1 country codes; 895 o clarified role of non-ISO prefix registry maintaind by the LoC; 897 o resolved inconsistency in lexical equivalence rules: as already 898 specified for ISO alpha-2 country-codes, and in accordance with 899 established practice, the whole NBN prefix is now declared case- 900 insensitive; 902 o registration template adapted to rfc3406bis[-00]; 904 o numerous editorial fixes and enhancements. 906 B.2. draft-ietf-urnbis-rfc3188bis-nbn-urn-00 to -01 908 o Numerous changes to accommodate the outcome of the discussions on 909 the urn list; 911 o three different ways of identifying fragments specified; 913 o removed some redundant/irrelevant paragraphs/subsections; 915 o the "one manifestation, one URN" principle strenghtened; 917 o introduced the idea of interlinking manifestations; 919 o extended the scope of the NBN explicitly to works; 921 o added reference to S4.2 in namespace registration; 923 o numerous editorial fixes and enhancements. 925 B.3. draft-ietf-urnbis-rfc3188bis-nbn-urn-01 to -02 927 o Removed the possibility of using prefixes not based on country 928 codes; 930 o replaced all instances of the word object with resources; 932 o removed some redundant/irrelevant paragraphs/subsections; 934 o allowed the possibility for identifying data elements with NBNs; 936 o a few editorial fixes and enhancements. 938 B.4. draft-ietf-urnbis-rfc3188bis-nbn-urn-02 to -03 940 o improved text related to "prefix" in NSS; 942 o addressed issues with text related to case-sensitivity of NSS 943 strings; 945 o addressed comments and open details on requirements language; 947 o switched language to talk about "resource" instead of "object"; 949 o several more editorial fixes and enhancements. 951 B.5. draft-ietf-urnbis-rfc3188bis-nbn-urn-03 to -04 953 o specification of how to use URN query and fragment part based on 954 the revised versions of rfc2141bis and rfc3406bis; 956 o various textual improvements and clarifications, including: 958 o textual alignments with rfc3187bis draft vers. -03; 960 o multiple editorial fixes and improvements. 962 B.6. draft-ietf-urnbis-rfc3188bis-nbn-urn-04 (2012-10-22) to draft- 963 hakala-urn-nbn-rfc3188bis-00 965 o Conversion of document to XML2RFC format, change of name (not a WG 966 task). 968 o Adjusted for changes to 2141bis, consolidation of RFC 3406bis, 969 creation of transition document. 971 o Made a number of changes to reflect publication of RFC 8141 972 (previously 2141bis and 3406bis) and update terminology, 973 references, and current status to early 2018. 975 Author's Address 977 Juha Hakala 978 The National Library of Finland 979 P.O. Box 15, Helsinki University 980 Helsinki, MA FIN-00014 981 Finland 983 Email: juha.hakala@helsinki.fi