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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 URNBIS P. Saint-Andre 3 Internet-Draft &yet 4 Obsoletes: 2141, 3406 (if approved) J. Klensin 5 Intended status: Standards Track March 9, 2015 6 Expires: September 10, 2015 8 Uniform Resource Names (URNs) 9 draft-ietf-urnbis-rfc2141bis-urn-10 11 Abstract 13 A Uniform Resource Name (URN) is a Uniform Resource Identifier (URI) 14 that is assigned under the "urn" scheme and a particular URN 15 namespace, typically with the intent that the URN will be a 16 persistent, location-independent resource identifier or abstract 17 designator. With regard to URN syntax, this document defines the 18 canonical syntax for URNs (in a way that is consistent with URI 19 syntax), specifies methods for determining URN equivalence, and 20 discusses URI conformance. With regard to URN namespaces, this 21 document specifies a method for defining a URN namespace and 22 associating it with a namespace identifier, and describes procedures 23 for registering namespace identifiers with the Internet Assigned 24 Numbers Authority (IANA). This document obsoletes both RFC 2141 and 25 RFC 3406. 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at http://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on September 10, 2015. 44 Copyright Notice 46 Copyright (c) 2015 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (http://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 This document may contain material from IETF Documents or IETF 60 Contributions published or made publicly available before November 61 10, 2008. The person(s) controlling the copyright in some of this 62 material may not have granted the IETF Trust the right to allow 63 modifications of such material outside the IETF Standards Process. 64 Without obtaining an adequate license from the person(s) controlling 65 the copyright in such materials, this document may not be modified 66 outside the IETF Standards Process, and derivative works of it may 67 not be created outside the IETF Standards Process, except to format 68 it for publication as an RFC or to translate it into languages other 69 than English. 71 Table of Contents 73 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 74 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 75 3. URN Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 5 76 3.1. Namespace Identifier Syntax . . . . . . . . . . . . . . . 5 77 3.2. Namespace Specific String Syntax . . . . . . . . . . . . 5 78 3.3. p-component, q-component, and f-component . . . . . . . . 6 79 4. Equivalence of URNs . . . . . . . . . . . . . . . . . . . . . 8 80 4.1. Procedure . . . . . . . . . . . . . . . . . . . . . . . . 8 81 4.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 9 82 5. URI Conformance . . . . . . . . . . . . . . . . . . . . . . . 10 83 6. URN Namespaces . . . . . . . . . . . . . . . . . . . . . . . 11 84 6.1. Formal Namespaces . . . . . . . . . . . . . . . . . . . . 13 85 6.2. Informal Namespaces . . . . . . . . . . . . . . . . . . . 15 86 7. Defining a URN Namespace . . . . . . . . . . . . . . . . . . 15 87 7.1. Purpose . . . . . . . . . . . . . . . . . . . . . . . . . 16 88 7.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 16 89 7.3. Assignment . . . . . . . . . . . . . . . . . . . . . . . 17 90 7.4. Security and Privacy . . . . . . . . . . . . . . . . . . 18 91 7.5. Resolution . . . . . . . . . . . . . . . . . . . . . . . 18 92 8. Registering a URN Namespace . . . . . . . . . . . . . . . . . 19 93 8.1. Formal Namespaces . . . . . . . . . . . . . . . . . . . . 19 94 8.2. Informal Namespaces . . . . . . . . . . . . . . . . . . . 19 95 9. Guidelines for Designated Experts . . . . . . . . . . . . . . 20 96 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 97 10.1. URI Scheme . . . . . . . . . . . . . . . . . . . . . . . 20 98 10.2. Registration of URN Namespaces . . . . . . . . . . . . . 21 99 11. Security and Privacy Considerations . . . . . . . . . . . . . 21 100 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 101 12.1. Normative References . . . . . . . . . . . . . . . . . . 22 102 12.2. Informative References . . . . . . . . . . . . . . . . . 22 103 Appendix A. Registration Template . . . . . . . . . . . . . . . 24 104 A.1. Namespace ID . . . . . . . . . . . . . . . . . . . . . . 24 105 A.2. Version . . . . . . . . . . . . . . . . . . . . . . . . . 24 106 A.3. Date . . . . . . . . . . . . . . . . . . . . . . . . . . 24 107 A.4. Registrant . . . . . . . . . . . . . . . . . . . . . . . 24 108 A.5. Purpose . . . . . . . . . . . . . . . . . . . . . . . . . 24 109 A.6. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 24 110 A.7. Assignment . . . . . . . . . . . . . . . . . . . . . . . 25 111 A.8. Resolution . . . . . . . . . . . . . . . . . . . . . . . 25 112 A.9. Documentation . . . . . . . . . . . . . . . . . . . . . . 25 113 A.10. Revision Information . . . . . . . . . . . . . . . . . . 25 114 Appendix B. Changes from RFC 2141 . . . . . . . . . . . . . . . 25 115 Appendix C. Changes from RFC 3406 . . . . . . . . . . . . . . . 25 116 Appendix D. Contributors . . . . . . . . . . . . . . . . . . . . 26 117 Appendix E. Acknowledgements . . . . . . . . . . . . . . . . . . 26 118 Appendix F. Change log for versions of draft-ietf-urnbis- 119 rfc2141bis-urn . . . . . . . . . . . . . . . . . . . 26 120 F.1. Changes from -08 to -09 . . . . . . . . . . . . . . . . . 26 121 F.2. Changes from -09 to -10 . . . . . . . . . . . . . . . . . 27 122 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27 124 1. Introduction 126 [[CREF1: Note on Draft -10: the editors had a choice between posting 127 this version in a stable, but early, form and waiting until the last 128 day for comment from the mailing list that might affect it. We chose 129 the latter but, since there have been few comments, the draft is a 130 little bit more rough in places, and contains more questions, than we 131 would have liked. Notes marked "WG:" are in particular need of 132 attention by the working group. References to "Henry" in those notes 133 are to various comments from Henry S. Thompson, so of which did not 134 appear on the mailing list. Similarly, reference to "Ted" are to Ted 135 Hardie's on-list messages of 3 March and discussions of them. We 136 hope those issues can be resolved on the mailing list or during IETF 137 92 and a new, cleaner, version posted at the end of the month.]] 139 A Uniform Resource Name (URN) is a Uniform Resource Identifier (URI) 140 [RFC3986] that is assigned under the "urn" scheme and a particular 141 namespace, typically with the intent that the URN will be a 142 persistent, location-independent resource identifier or abstract 143 designator. 145 The assignment of URNs is done by an organization (or, in some cases, 146 according to an algorithm or other automated process) that has been 147 formally delegated a namespace within the "urn" scheme (e.g., a URN 148 in the 'example' namespace [RFC6963] might be of the form 149 "urn:example:foo"). 151 This document rests on two key assumptions: 153 1. Assignment of a URN is a managed process. 155 2. The space of URN namespaces is itself managed. 157 While other schemes may allow identifiers to be freely chosen and 158 assigned, this is not the case for URNs. The syntactical correctness 159 of a string appearing after "urn:" is not sufficient to make it a 160 URN; both the namespace identifier and namespace specific string must 161 be registered or generated according to the rules given for it to be 162 a valid URN. 164 So that information about both URN syntax and URN namespaces is 165 available in one place, this document does the following: 167 1. Defines the canonical syntax for URNs in general (in a way that 168 is consistent with URI syntax), specifies methods for determining 169 URN equivalence, and discusses URI conformance. 171 2. Specifies a method for defining a URN namespace and associating 172 it with a namespace identifier, and describes procedures for 173 registering namespace identifiers with the Internet Assigned 174 Numbers Authority (IANA). 176 For URN syntax and URN namespaces, this document modernizes and 177 replaces the definitions from [RFC2141] and [RFC3406]. These 178 modifications build on the requirements provided in [RFC1737] and 179 many years of experience with URNs, in both cases attempting to make 180 the smallest reasonable set of changes from the previous definitions. 182 This document obsoletes both [RFC2141] and [RFC3406]. 184 2. Terminology 186 Several important terms used in this document are defined in the URI 187 specification [RFC3986]. 189 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 190 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 191 "OPTIONAL" in this document are to be interpreted as described in 192 [RFC2119]. 194 3. URN Syntax 196 The syntax of URNs as provided in [RFC2141] was defined before the 197 updated specification of URIs in [RFC3986]. To ensure consistency 198 with the URI syntax as well as semantic flexibility in the use of 199 URNs within particular applications (see 200 [I-D.ietf-urnbis-semantics-clarif] for further discussion), this 201 specification extends the syntax of URNs to explicitly allow several 202 characters (and thus URI components) that were not allowed by 203 [RFC2141], and also makes several smaller syntax adjustments. 205 As a result, the syntax for a URN is defined as follows using the 206 Augmented Backus-Naur Form (ABNF) as specified in [RFC5234]. Rules 207 not defined below (i.e., alphanum, pchar, path-absolute, query, and 208 fragment) are defined in [RFC3986]. 210 namestring = assigned-name 211 [ p-component ] 212 [ q-component ] 213 [ f-component ] 214 assigned-name = "urn" ":" NID ":" NSS 215 ; the URI scheme ("urn") is case insensitive 216 NID = (alphanum) 0*30(ldh) (alphanum) 217 ldh = alphanum / "-" 218 NSS = 1*(pchar) 219 p-component = "/" path-absolute 220 q-component = "?" query 221 f-component = "#" fragment 223 Note that "?" can be used without %-encoding inside q-components and 224 f-components. 226 The following sections provide additional information about these 227 rules. 229 3.1. Namespace Identifier Syntax 231 The syntax here is slightly more restrictive than what was defined in 232 [RFC2141], since it forbids the character "-" at the end of a NID. 234 NIDs are case insensitive (e.g., "ISBN" and "isbn" are equivalent). 236 3.2. Namespace Specific String Syntax 238 [[CREF2: -09 text follows; see below:]] Depending on the rules 239 governing a namespace, names that are valid in a namespace might 240 contain characters that are not allowed in URNs according to the 241 "pchar" rule (e.g., characters outside the ASCII range or characters 242 that are reserved in URIs, such as "/", "?", and "#"). Such a string 243 MUST be translated into a conformant NSS before using it as a 244 protocol element or otherwise passing it on to other applications. 245 Translation is done by percent-encoding each disallowed character 246 using the method defined in Section 2.1 of [RFC3986]. Note that the 247 "%" character is allowed only for the purpose of percent-encoding. 248 [[CREF3: WG: note Ted's suggested replacement text (email of 249 2015-03-06 and and below: ]] 250 [[CREF4: Edited version of Ted's proposal for replacement text -- the 251 WG needs to decide whether to use it and, if so to check it 252 carefully:]] 253 Depending on the rules governing a namespace, names that are valid in 254 a namespace might contain characters that are not found in the 255 "pchar" production above (e.g., characters outside the ASCII range or 256 characters that are reserved in URIs, such as "/", "?", and "#"). 257 While these may be valid names, they are not valid URNs until those 258 strings are translated into a conformant NSS. Translation is done by 259 percent-encoding each disallowed character using the method defined 260 in Section 2.1 of the generic URI specification [RFC3986] Note that 261 the "%" character is allowed only for the purpose of percent- 262 encoding. 264 In order to make URNs as stable and persistent as possible when 265 protocols evolve and the environment around them changes, namespaces 266 SHOULD NOT allow characters outside the basic Latin repertoire 267 [RFC20] unless the nature of the particular namespace makes such 268 characters necessary. 270 If a namespace designates one or more characters conforming to the 271 "pchar" rule as having special meaning for that namespace (e.g., "@") 272 and the namespace also uses that character in a literal sense, when 273 used in a literal sense the character MUST be percent-encoded (e.g., 274 "%40"). For related considerations with regard to NID registration, 275 see below. 277 3.3. p-component, q-component, and f-component 279 The p-component, q-component, and f-component are optional components 280 that follow the assigned-name. In terms of URI syntax these 281 components are essentially equivalent to the URI "path-absolute", 282 "query", and "fragment" constructions, respectively. However, the 283 URN p-component, q-component, and f-component need not be 284 semantically equivalent to the URI path component, query component, 285 and fragment component; therefore they are called by different names 286 in this specification. 288 Unless specifically defined for a particular namespace after 289 publication of this document, use of these components is disallowed, 290 thereby maintaining strict backward compatibility with namespaces 291 defined in accordance with [RFC2141] and registered in accordance 292 with [RFC3406]. 294 This specification does not define the semantics of the p-component, 295 q-component, and f-component for URNs in general. Instead, 296 additional specifications might establish these matters for URN- 297 related services (such as URN resolution) or for individual URN 298 namespaces (e.g., to handle extended information about the resource 299 identified by a URN). For example, it is possible that the 300 q-component might be used in requests to URN resolution services, or 301 that the f-component might be used to distinguish the integral parts 302 of resources named by URNs in particular namespaces (say, the 303 chapters of a book). However, defining such usage is the 304 responsibility of specifications for URN resolution services, 305 namespace registration requests and specifications for individual 306 namespaces, and other appropriate documentation (such as policy 307 documents governing the management of a given URN namespace). 309 As general guidance that might not apply to all cases, it would be 310 inappropriate for namespaces that do not intend to support resolution 311 services to allow q-components. Namespaces that deal with digital 312 manifestations might be able to support f-components. 313 [[CREF5: WG: What, if anything, should be said about p-components 314 here? ]] 316 3.3.1. p-component 318 The only formal restriction placed upon a p-component by this 319 specification is that the syntax SHALL adhere to the "path-absolute" 320 rule from [RFC3986]. The inner syntax of a p-component is to be 321 defined by the specification for a particular namespace or URN- 322 related service. (For example, a namespace specification might 323 define a character such as "~" or "@" as a delimiter inside 324 p-components assigned within that namespace.) 326 As described under Section 4, the p-component SHALL be taken into 327 account when determining URN equivalence. 329 3.3.2. q-component 331 The only formal restriction placed upon a q-component by this 332 specification is that the syntax SHALL adhere to the "query" rule 333 from [RFC3986] (prepended by the "?" character). The inner syntax of 334 a q-component is to be defined by the specification for a particular 335 namespace. (For example, a namespace specification might define a 336 character such as ";" or "=" as a delimiter inside q-components 337 assigned within that namespace.) 338 As described under Section 4, the q-component SHALL NOT be taken into 339 account when determining URN equivalence. 341 3.3.3. f-component 343 The only formal restriction placed upon an f-component by this 344 specification is that the syntax SHALL adhere to the "fragment" rule 345 from [RFC3986] (prepended by the "#" character). The inner syntax of 346 an f-component is to be defined by the specification for a particular 347 namespace. (For example, a namespace specification might define a 348 character such as "&" or "+" as a delimiter inside f-components 349 assigned within that namespace.) 351 As described under Section 4, the f-component SHALL NOT be taken into 352 account when determining URN equivalence. 354 4. Equivalence of URNs 356 4.1. Procedure 358 For various purposes such as caching, often it is desirable to 359 determine if two URNs are "the same". This is done by testing for 360 equivalence (see Section 6.1 of [RFC3986]). 362 The generic URI specification [RFC3986] is very flexible about 363 equality comparisons, putting the focus on allowing false negatives 364 and avoiding false positives. If comparisons are made in a scheme- 365 independent way, i.e., as URI comparisons only, URNs that this 366 specification considers equal would be rejected. The discussion 367 below applies when the URIs involved are known to be URNs. 369 Two URNs are equivalent if they are octet-by-octet equal after 370 applying case normalization (as specified in Section 6.2.2.1 of 371 [RFC3986]) to the following constructs: 372 [[CREF6: WG: See a variety of notes about "case normalization" and 373 related issues, e.g., the tracker entry 374 https://github.com/MelindaShore/urnbis/issues/3 ]] 376 1. the URI scheme "urn" 378 2. the NID 380 3. any percent-encoded characters in the NSS (that is, all character 381 triplets in the NSS that match the production 382 found in Section 2.1 of the base URI specification [RFC3986]). 384 Percent-encoded characters MUST NOT be decoded, i.e., percent- 385 encoding normalization (as specified in Section 6.2.2.2 of [RFC3986]) 386 MUST NOT be applied. 388 [[CREF7: WG: Ted's note of 2015-03-06 recommends adding p-component 389 here somewhere. If we do so, we need to be sure that the new text 390 doesn't accidentally make them case-insensitive again.]] 392 If a q-component or f-component (or both) are included in a URN, they 393 MUST be ignored for purposes of determining equivalence. 395 URN namespace definitions may include additional rules for 396 equivalence, such as case-insensitivity of the NSS (or parts 397 thereof). Such rules MUST always have the effect of eliminating some 398 of the false negatives obtained by the procedure above and MUST NOT 399 result in treating two URNs as not equivalent if the procedure here 400 says they are equivalent. For related considerations with regard to 401 NID registration, see below. 403 4.2. Examples 405 The following six URN comparisons (which use the "example" NID 406 defined in [RFC6963]) highlight the equivalence rules: 408 1. URN:example:a123,456 410 2. urn:example:a123,456 412 3. urn:EXAMPLE:a123,456 414 4. urn:example:a123%2C456 416 5. URN:EXAMPLE:a123%2c456 418 6. urn:example:A123,456 420 7. urn:example:a123,456/789 422 8. urn:example:a123,456/abc 424 9. urn:example:a123,456?789 426 10. urn:example:a123,456?abc 428 11. urn:example:a123,456#789 430 12. urn:example:a123,456#abc 431 URNs 1, 2, 3, 9, 10, 11, and 12 are equivalent. URNs 4 and 5 are 432 equivalent only to each other. URNs 6, 7, and 8 are not equivalent 433 to any of the others. 435 [[CREF8: Placeholder: We should still add some examples with p-, q-, 436 and/or f-components to the above list. ]] 438 5. URI Conformance 440 Because a URN is, syntactically, a URI under the "urn" scheme, in 441 theory a URN can be placed in any protocol slot that allows for a URI 442 (e.g., an XML namespace name [XML-NAMES]). However, this does not 443 imply that, semantically, it always makes sense in practice to place 444 a URN in a given URI protocol slot; in particular, because a URN 445 might not specify the location of a resource or even point indirectly 446 to one, it might not be appropriate to place a URN in a URI protocol 447 slot that points to a resource (examples include the 'href' and 'src' 448 attributes and the element in HTML, as well as the 'xml:base' 449 attribute in XML [XML-BASE]). Ultimately, specifications of where it 450 is appropriate to use URNs, or URNs created within particular URN 451 namespaces, are the responsibility of descriptions of individual URI 452 schemes and their expected uses; this specification cannot possibly 453 anticipate all of the relevant cases. 454 [[CREF9: Ted suggests "...individual URI contexts;"]] 456 Despite the fact that URNs are not hierarchical and are not 457 appropriate for use as a base URI (see Section 5.1 of [RFC3986]), the 458 relative resolution algorithm specified in Section 5.2 of [RFC3986] 459 still applies to the "urn" URI scheme; implementers need to be aware, 460 however, that running the algorithm against URNs will lead to results 461 that might be unexpected or not useful. 463 A resolver that conforms to the URI specification [RFC3986] will 464 extract a scheme of "urn" rather than a scheme value of "urn:". 465 [[CREF10: WG: Henry has pointed out that this spec really cannot 466 constrain generic URI resolvers (or processors more generally. Is 467 the following rewrite of 'A URN MUST be considered an opaque URI by 468 URI resolvers and passed (with the "urn" scheme) to a URN resolver 469 for resolution.' sufficient.]] 470 In part because of the separation of semantics from syntax 471 [I-D.ietf-urnbis-semantics-clarif], generic URI processors must pay 472 special attention to the parsing and analysis rules of RFC 3986 and, 473 in particular, must treat the URI as opaque unless the scheme and its 474 requirements are recognized. The URN resolver can either be an 475 external resolver that the URI resolver knows of, or it can be 476 functionality built into the URI resolver. Note that this 477 requirement MAY impose constraints on the contexts in which URNs are 478 appropriately used; see the previous section. 480 To minimize user confusion, a URI browser SHOULD display the complete 481 URN (including the "urn" scheme and any components) to ensure that 482 there is no confusion between URN namespace identifiers and URI 483 scheme identifiers. For example, a URI beginning with "urn:xmpp:" 484 [RFC4854] is very different from a URI beginning with "xmpp:" 485 [RFC5122]. Similarly, a potential DOI scheme [DOI-URI] is different 486 from, and possibly completely unrelated to, a possible DOI URN 487 namespace. 489 When URNs are transported and exchanged, they MUST be represented in 490 this format. Further, all URN-aware applications MUST offer the 491 option of displaying URNs in this canonical form to allow for direct 492 transcription (for example by cut and paste techniques). Such 493 applications might support display of URNs in a more human-friendly 494 form and might use a character set that includes characters that are 495 not permitted in URN syntax as defined in this specification (e.g., 496 when displaying URNs to humans, such applications might replace 497 percent-encoded strings with characters from an extended character 498 repertoire such as that of [UNICODE]). 500 As mentioned, the assignment of URNs is a managed process, as is the 501 assignment of namespaces themselves. Although design of the URNs to 502 be assigned within a given namespace is ceded by this specification 503 to the namespace owner, doing so in a managed way avoids the problems 504 inherent in unmanaged generation of URIs as described in the 505 recommendations regarding URI design and ownership [RFC7320]. 507 6. URN Namespaces 509 A URN namespace is a collection of identifiers that obey three 510 constraints. Such a namespace is (1) unique, (2) assigned in a 511 consistent way, and (3) assigned according to a common definition. 513 1. The "uniqueness" constraint means that an identifier within the 514 namespace is never assigned to more than one resource and never 515 reassigned to a different resource, even if the identifier itself 516 is deprecated or becomes obsolete. 518 2. The "consistent assignment" constraint means that an identifier 519 within the namespace is assigned by an organization or created in 520 accordance with a process or algorithm that is always followed. 522 3. The "common definition" constraint means that there are clear 523 definitions for the syntax of identifiers within the namespace 524 and for the process of assigning or creating them. 526 A URN namespace is identified by a particular NID in order to ensure 527 the global uniqueness of URNs and, optionally, to provide a cue 528 regarding the structure of URNs assigned within a namespace. 530 With regard to global uniqueness, using different NIDs for different 531 collections of identifiers ensures that no two URNs will be the same 532 for different resources, since each collection is required to 533 uniquely assign each identifier. However, a single resource can have 534 more than one URN assigned to it for different purposes (e.g., some 535 numbers might be valid identifiers in two different identifier 536 systems, where the namespace identifier differentiates between the 537 resulting URNs). Subject to other constraints, such as those imposed 538 by the URI syntax [RFC3986], the rules of the URN scheme are intended 539 to allow preserving the normal and natural form of identifiers 540 specified elsewhere and treated as URN namespaces. 542 [[CREF11: WG: Ted suggested adding a concrete example, "as this seems 543 likely to be open to confusion. The RFC 5031 emergency services may 544 provide one (e.g. urn:service:counseling.mental-health and 545 urn:service:counseling.suicide may be the same resource), but any 546 concrete example would likely be an improvement." Is that example 547 ok? Would anyone like to suggest other text or an additional 548 example?]] 550 With regard to the structure of URNs assigned within a namespace, the 551 development of an identifier structure (and thereby a collection of 552 identifiers) depends on the requirements of the community defining 553 the identifiers, how the identifiers will be assigned and used, etc. 554 These issues are beyond the scope of URN syntax and the general rules 555 for URN namespaces, because they are specific to the community 556 defining a namespace (e.g., the bibliographic and publishing 557 communities in the case of the 'ISBN' and 'ISSN' namespaces, or the 558 developers of extensions to the Extensible Messaging and Presence 559 Protocol in the case of the 'XMPP' namespace). 561 URN namespaces inherit certain rights and responsibilities by the 562 nature of URNs, e.g.: 564 1. They uphold the general principles of a well-managed URN 565 namespace by providing persistent identification of resources and 566 unique assignment of identifier strings. 568 2. They can be registered in global registration services. 570 There are two types of URN namespace: formal and informal. These are 571 distinguished by the expected level of service, the information 572 needed to define the namespace, and the procedures for registration. 574 Because the majority of the namespaces registered so far have been 575 formal, this document concentrates on formal namespaces. 577 Note: [RFC3406] defined a third type of "experimental namespaces", 578 denoted by prefixing the namespace identifier with the string "X-". 579 Consistent with [RFC6648], this specification removes the 580 experimental category. Because experimental namespaces were never 581 registered, removing the experimental category has no impact on the 582 existing registries or future registration procedures. Because they 583 are not registered, strings that refer to existing experimental 584 namespaces are not valid URNs. Truly experimental usages can, of 585 course, employ the 'example' namespace [RFC6963]. 587 6.1. Formal Namespaces 589 A formal namespace provides benefit to some subset of users on the 590 Internet. In particular, it would not make sense for a formal 591 namespace to be used only by a community or network that is not 592 connected to the Internet. For example, it would be inappropriate 593 for a NID to effectively force someone to use a proprietary network 594 or service not open to the general Internet user. The intent is 595 that, while the community of those who might actively use the names 596 assigned within that NID might be small, the potential use of 597 identifiers within that NID is open to any user on the Internet. 598 Formal NIDs might be appropriate even when some aspects are not fully 599 open. For example, a namespace might make use of a fee-based, 600 privately managed, or proprietary registry for assignment of URNs in 601 the namespace. However, it might still benefit some Internet users 602 if the associated services have openly-published access protocols. 604 An organization that will assign URNs within a formal namespace ought 605 to meet the following criteria: 607 1. Organizational stability and the ability to maintain the URN 608 namespace for a long time; absent such evidence, it ought to be 609 clear how the namespace can remain viable if the organization can 610 no longer maintain the namespace. 612 2. Competency in name assignment. This will improve the likelihood 613 of persistence (e.g. to minimize the likelihood of conflicts). 615 3. Commitment to not reassigning existing names and to allowing old 616 names to continue to be valid, even if the owners or assignees of 617 those names are no longer members or customers of that 618 organization. With regard to URN resolution [RFC2276], this does 619 not mean that there needs to be resolution of such names, only 620 that the names will not resolve to false or stale information. 622 [[CREF12: WG: Henry says "Really? If a piece of retrievable 623 metadata for some URN is the name and (postal) address of the 624 publisher of whatever it identifies, and they've gone out of 625 business, that metadata is necessarily stale, isn't it?" How do 626 you think this should be handled?]] 628 A formal namespace establishes a particular NID, subject to the 629 following constraints (above and beyond the syntax rules already 630 specified): 632 1. It MUST NOT be an already-registered NID. 634 2. It MUST NOT start with "urn-" (which is reserved for informal 635 namespaces). 637 3. It MUST be more than two characters long. 639 4. It MUST NOT start with "aa-", where "aa" is any combination of 640 two ASCII letters and the hyphen is followed by something other 641 than another hyphen. 643 5. It MUST NOT start with the string "xn--" or any other string 644 consisting of two letters followed by two hyphens. Those strings 645 are reserved for potential representation of DNS A-labels and 646 similar strings in the future [RFC5890]. 647 [[CREF13: Note in Draft: IDNA reserves the entire collection of 648 strings starting with two characters followed by two hyphens.]] 650 6. [[CREF14: WG: Ted also points out that proposed NIDs that are, or 651 resemble, ISO 3166-1 alpha-3 codes may need special consideration 652 in expert review becuase some countries claim ownership of them 653 (and, at least implicitly, their use by anyone other than that 654 country could be deceptive. On a related and more general note, 655 Henry inquired whether we need dispute resolution and/or 656 trademark procedures. The WG needs to decide whether to address 657 those issues and, if so, how.]] 659 All two-letter strings, and all two-letter strings followed by "-" 660 and any sequence of valid NID characters, are reserved for potential 661 use as NIDs based on ISO alpha-2 country codes [ISO3166] for eventual 662 national registrations of URN namespaces. The definition and scoping 663 of rules for allocation of responsibility for such country-code-based 664 namespaces is beyond the scope of this document. 666 6.2. Informal Namespaces 668 Informal namespaces are full-fledged URN namespaces, with all the 669 associated rights and responsibilities. Informal namespaces differ 670 from formal namespaces in the process for assigning a NID: for an 671 informal namespace, the registrant does not designate the NID; 672 instead, IANA assigns a NID consisting of the string 'urn-' followed 673 by one or more digits (e.g., "urn-7") where the digits consist of the 674 next available number in the sequence of positive integers assigned 675 to informal namespaces. Thus the syntax of an informal namespace is: 677 InformalNamespaceName = "urn-" Number 678 Number = DigitNonZero 0*Digit 679 DigitNonZero = "1"/ "2" / "3" / "4"/ "5" 680 / "6" / "7" / "8" / "9" 681 Digit = "0" / DigitNonZero 683 The only restrictions on are that it (1) consist strictly of 684 ASCII digits, that it (2) not have leading zeros, and that it (3) not 685 cause the NID to exceed the length limitations defined for the URN 686 syntax. 688 7. Defining a URN Namespace 690 The material in this section is intended as guidance to both 691 designers of URN namespaces and (expert) reviewers of proposed URN 692 namespace registrations. More information for the latter appears in 693 Section 9. 694 [[CREF15: WG: Henry would like to see a SHOULD requirement on the 695 definitions here. The WG needs to decide whether that is necessary 696 and/or desirable.]] 698 The definition of a formal namespace ought to pay particular 699 attention to: 701 1. The purpose of the namespace. 703 2. The syntax of URNs assigned within the namespace, including 704 whether p-, q-, and/or f-components are allowed. 706 3. The process for assigning URNs within the namespace. 708 4. The security implications of assigning URNs within the namespace 709 and using the assigned URNs. 711 5. Optionally, the process for resolving URNs issued within the 712 namepace. 714 The following sections explain these matters in greater detail. For 715 convenience, a template for defining and registering a URN namespace 716 is provided under Appendix A. This information can be especially 717 helpful to entities that wish to request assignment of a URN in a 718 namespace and to entities that wish to provide URN resolution for a 719 namespace. 721 7.1. Purpose 723 The "Purpose" section of the template describes matters such as: 725 1. The kinds of resources identified by URNs assigned within the 726 namespace. 728 2. Why it is preferable to use URNs rather than some other 729 technology (e.g., separate URI schemes or URIs in existing 730 schemes) and why no existing URN namespace is a good fit. 732 3. The kinds of software applications that can use or resolve the 733 assigned URNs (e.g., by differentiating among disparate 734 namespaces, identifying resources in a persistent fashion, or 735 meaningfully resolving and accessing services associated with the 736 namespace). 738 4. The scope of the namespace (public vs. private, global vs. local 739 to a particular organization, nation, or industry). For example, 740 a namespace claiming to deal in "national identification numbers" 741 ought to have a global scope and address all identity number 742 structures, whereas a URN scheme for a particular national 743 identification number system would need to handle only the 744 structure for that nation's identity numbers. 746 5. How the intended community (and the Internet community at large) 747 will benefit from using or resolving the assigned URNs. 749 7.2. Syntax 751 The "Syntax" section of the template contains: 753 1. A description of the structure of URNs within the namespace, in 754 conformance with the fundamental URN syntax. The structure might 755 be described in terms of a formal definition (e.g., using 756 Augmented BNF for Syntax Specifications (ABNF) as specified in 757 [RFC5234]), an algorithm for generating conformant URNs, or a 758 regular expression for parsing the identifier into components; 759 alternatively, the structure might be opaque. 761 2. Any special character encoding rules for assigned URNs (e.g., 762 which character ought to always be used for single-quotes). 764 3. If p-components, q-components, and/or f-components are allowed 765 for the namespace, a discussion of how they are used. 767 4. Rules for determining equivalence between two identifiers in the 768 namespace. Such rules ought to always have the effect of 769 eliminating false negatives that might otherwise result from 770 comparison. If it is appropriate and helpful, reference can be 771 made to specific equivalence rules defined in the URI 772 specification [RFC3986]. Examples of equivalence rules include 773 equivalence between uppercase and lowercase characters in the 774 Namespace Specific String, between hyphenated and non-hyphenated 775 groupings in the identifier string, or between single-quotes and 776 double-quotes. (Note that these are not normative statements for 777 any kind of best practice related to handling of equivalences 778 between characters in general; they are statements limited to one 779 particular namespace only.) 781 5. Any special considerations necessary for conforming with the URN 782 syntax. This is particularly applicable in the case of existing 783 naming systems that are used in the context of URNs. For 784 example, if a namespace is used in contexts other than URNs, it 785 might make use of characters that are reserved in the URN syntax. 786 This section ought to note any such characters, and outline 787 necessary mappings to conform to URN syntax. Normally, this will 788 be handled by percent-encoding the character as specified in the 789 URI specification [RFC3986]. 791 7.3. Assignment 793 The "Assignment" section of the template describes matters such as: 795 1. Mechanisms or authorities for assigning URNs to resources. It 796 ought to make clear whether assignment is completely open (e.g., 797 following a particular procedure such as first-come, first-served 798 (FCFS)), completely closed (e.g., for a private organization), or 799 limited in various ways (e.g., delegated to authorities 800 recognized by a particular organization); if limited, it ought to 801 explain how to become an assigner of identifiers or how to 802 request assignment of identifiers from existing assignment 803 authorities. 805 2. Methods for ensuring that URNs within the namespace are unique. 806 For example, identifiers might be assigned sequentially or in 807 accordance with some well-defined process by a single authority, 808 assignment might be partitioned among delegated authorities that 809 are individually responsible for respecting uniqueness rules, or 810 URNs might be created independently following an algorithm that 811 itself guarantees uniqueness. 813 7.4. Security and Privacy 815 The "Security" section of the template describes any potential issues 816 related to security and privacy with regard to assignment, use, and 817 resolution of identifiers within the namespace. Examples of such 818 issues include: 820 o The consequences of producing false negatives and false positives 821 during comparison for equivalence (see "Issues in Identifier 822 Comparison for Security Purposes" [RFC6943]) 824 o Leakage of private information when identifiers are communicated 825 on the public Internet 827 o The potential for directory harvesting 829 o Various issues discussed in the guidelines for security 830 considerations in RFCs [RFC3552] and the privacy considerations 831 for Internet protocols [RFC6973]. 833 7.5. Resolution 835 The "Resolution" section specifies the rules for resolution of URNs 836 assigned within the namespace. If such URNs are intended to be 837 resolvable, the namespace needs to be registered in a Resolution 838 Discovery System (RDS, see [RFC2276]) such as DDDS. Resolution then 839 proceeds according to standard URI resolution processes, as well as 840 the mechanisms of the RDS. This section ought to list the 841 requirements for becoming a recognized resolver of URNs in the 842 relevant namespace (and being so listed in the RDS registry). 843 Answers might include, but are not limited to: 845 [[CREF16: WG: Possible alternate paragraph instead of above, see 846 email from Klensin, 2015-03-04, subject: "Resolution services and 847 Section 7.5 of draft-ietf-urnbis-rfc2141bis-urn-09": The "Resolution" 848 section specifies the rules for resolution of URNs assigned within 849 the namespace. This section SHOULD list the requirements for 850 becoming a recognized resolver of URNs in the relevant namespace. 851 Answers might include, but are not limited to:]] 853 1. The namespace is not listed with an RDS; therefore this section 854 is not applicable. 856 2. Resolution mirroring is completely open, with a mechanism for 857 updating an appropriate RDS. 859 3. Resolution is controlled by entities to which assignment has been 860 delegated. 862 8. Registering a URN Namespace 864 [[CREF17: WG: As pointed out on the mailing list (message from 865 Klensin, 4 March 10:16 -0500, subject: "Expert reveiw and draft-ietf- 866 urnbis-rfc2141bis-urn-09"), we've had several discussions that 867 suggest a somewhat different Expert Review model than is covered by 868 RFC 5226. Those discussions haven't gotten quite far enough to let 869 us generate specific text, so the WG has work to do in this area. 870 That email message makes a suggestion.]] 872 8.1. Formal Namespaces 874 The registration policy for formal namespaces is Expert Review as 875 defined in the "IANA Considerations" document [RFC5226] and in 876 Section 9 below. The key steps for registration of a formal 877 namespace are: 879 1. Fill out the namespace registration template (see Appendix A). 880 This can be done as part of an Internet-Draft or a specification 881 in another series, although that is not necessary. 883 2. Send the completed template to the urn-nid@ietf.org discussion 884 list for review. 886 3. If necessary to address comments received, repeat steps 1 and 2. 888 4. If the designated experts approve the request, the IANA will 889 register the requested NID. 891 A formal namespace registration can be revised by updating the 892 registration template, following the same steps outlined above for 893 new registrations. A revised registration MUST describe differences 894 from prior versions and SHOULD make special note of any relevant 895 changes in the underlying technologies or namespace management 896 processes. 898 8.2. Informal Namespaces 900 The registration policy for informal namespaces is First Come First 901 Served [RFC5226]. The key steps for registration of an informal 902 namespace are: 904 1. Write a completed namespace definition template (see Appendix A). 906 2. Send it to the urn-nid@ietf.org discussion list for feedback. 908 3. Once the review period has expired, send the final template to 909 IANA (via the iana@iana.org email address). 911 An informal namespace registration can be revised by updating the 912 registration template, following the same steps outlined above for 913 new registrations. 915 9. Guidelines for Designated Experts 917 Experience to date with NID registration requests has shown that 918 registrants sometimes do not initially understand some of the 919 subtleties of URN namespaces, and that defining the namespace in the 920 form of a specification enables the registrants to clearly formulate 921 their "contract" with the intended user community. Therefore, 922 although the registration policy for formal namespaces is Expert 923 Review and a stable specification is not strictly required, the 924 designated experts for NID registration requests ought to encourage 925 applicants to provide a stable specification documenting the 926 namespace definition. 928 Naming can be difficult and contentious; the designated experts and 929 applicants are strongly encouraged to work together in a spirit of 930 good faith and mutual understanding to achieve rough consensus on 931 progressing registrations through the process. They are also 932 encouraged to bring additional expertise into the discussion if that 933 would be helpful in adding perspective or otherwise resolving issues. 935 10. IANA Considerations 937 10.1. URI Scheme 939 This section updates the registration of the 'urn' URI scheme in the 940 Permanent URI Registry [URI-Registry] . 942 [Note to RFC Editor: please replace "XXXX" with the number assigned 943 to this document upon publication.] 945 URI Scheme Name: urn 947 Status: permanent 949 URI Scheme Syntax: See Section 3 of [ this document ]. 951 URI Scheme Semantics: The 'urn' scheme identifies Uniform Resource 952 Names, which are persistent, location-independent resource 953 identifiers. 955 Encoding Considerations: See Section 3.2 of [ this document ]. 957 Applications/Protocols That Use This URI Scheme Name: Uniform 958 Resource Names are used in a wide variety of applications, 959 including bibliographic reference systems and as names for 960 Extensible Markup Language (XML) namespaces. 962 Interoperability Considerations: See Section 5 of [ this document ]. 963 [[CREF18: WG: More text needed, possibly along the lines of Juha's 964 posting of Tuesday, January 13, 2015 14:45 +0200, Subject: Re: 965 [urn] IANA considerations and interoperability]] 967 Security Considerations: See Section 7.4 and Section 11 of [ this 968 document ]. 970 Contact: URNBIS WG [mailto:urn@ietf.org] 972 Author/Change Controller: This scheme is registered under the IETF 973 tree. As such, the IETF maintains change control. 975 References None. 977 10.2. Registration of URN Namespaces 979 This document outlines the processes for registering URN namespaces, 980 and has implications for the IANA in terms of registries to be 981 maintained. In all cases, the IANA ought to assign the appropriate 982 NID (formal or informal) once the procedures outlined in this 983 document have been completed. 985 11. Security and Privacy Considerations 987 The definition of a URN namespace needs to account for potential 988 security and privacy issues related to assignment, use, and 989 resolution of identifiers within the namespace (e.g., some namespace 990 resolvers might assign special meaning to certain characters in the 991 Namespace Specific String); see Section 7.4 for further discussion. 993 In most cases, URN namespaces provide a way to declare public 994 information. Nominally, these declarations will have a relatively 995 low security profile, however there is always the danger of 996 "spoofing" and providing misinformation. Information in these 997 declarations ought to be taken as advisory. 999 12. References 1001 12.1. Normative References 1003 [RFC20] Cerf, V., "ASCII format for network interchange", RFC 20, 1004 October 1969. 1006 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1007 Requirement Levels", BCP 14, RFC 2119, March 1997. 1009 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 1010 Resource Identifier (URI): Generic Syntax", STD 66, RFC 1011 3986, January 2005. 1013 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 1014 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 1015 May 2008. 1017 [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax 1018 Specifications: ABNF", STD 68, RFC 5234, January 2008. 1020 [URI-Registry] 1021 IANA, "Permanent URI Schemes", 1022 . 1025 [ISO3166] ISO, "Codes for the representation of names of countries 1026 and their subdivisions -- Part 1: Country codes", ISO 1027 3166-1:2013, 2013. 1029 12.2. Informative References 1031 [I-D.ietf-urnbis-semantics-clarif] 1032 Klensin, J., "URN Semantics Clarification", draft-ietf- 1033 urnbis-semantics-clarif-01 (work in progress), February 1034 2015. 1036 [DOI-URI] Paskin, N., Neylon, E., Hammond, T., and S. Sun, "The 1037 "doi" URI Scheme for the Digital Object Identifier (DOI)", 1038 June 2003, 1039 . 1041 [RFC1737] Sollins, K. and L. Masinter, "Functional Requirements for 1042 Uniform Resource Names", RFC 1737, December 1994. 1044 [RFC2141] Moats, R., "URN Syntax", RFC 2141, May 1997. 1046 [RFC2276] Sollins, K., "Architectural Principles of Uniform Resource 1047 Name Resolution", RFC 2276, January 1998. 1049 [RFC3406] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom, 1050 "Uniform Resource Names (URN) Namespace Definition 1051 Mechanisms", BCP 66, RFC 3406, October 2002. 1053 [RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC 1054 Text on Security Considerations", BCP 72, RFC 3552, July 1055 2003. 1057 [RFC4854] Saint-Andre, P., "A Uniform Resource Name (URN) Namespace 1058 for Extensions to the Extensible Messaging and Presence 1059 Protocol (XMPP)", RFC 4854, April 2007. 1061 [RFC5122] Saint-Andre, P., "Internationalized Resource Identifiers 1062 (IRIs) and Uniform Resource Identifiers (URIs) for the 1063 Extensible Messaging and Presence Protocol (XMPP)", RFC 1064 5122, February 2008. 1066 [RFC5890] Klensin, J., "Internationalized Domain Names for 1067 Applications (IDNA): Definitions and Document Framework", 1068 RFC 5890, August 2010. 1070 [RFC6648] Saint-Andre, P., Crocker, D., and M. Nottingham, 1071 "Deprecating the "X-" Prefix and Similar Constructs in 1072 Application Protocols", BCP 178, RFC 6648, June 2012. 1074 [RFC6943] Thaler, D., "Issues in Identifier Comparison for Security 1075 Purposes", RFC 6943, May 2013. 1077 [RFC6963] Saint-Andre, P., "A Uniform Resource Name (URN) Namespace 1078 for Examples", BCP 183, RFC 6963, May 2013. 1080 [RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., 1081 Morris, J., Hansen, M., and R. Smith, "Privacy 1082 Considerations for Internet Protocols", RFC 6973, July 1083 2013. 1085 [RFC7320] Nottingham, M., "URI Design and Ownership", BCP 190, RFC 1086 7320, July 2014. 1088 [UNICODE] The Unicode Consortium, "The Unicode Standard, Version 1089 6.3", 2013, 1090 . 1092 [XML-BASE] 1093 Marsh, J. and R. Tobin, "XML Base (Second Edition)", World 1094 Wide Web Consortium Recommendation REC-xmlbase-20090128, 1095 January 2009, 1096 . 1098 [XML-NAMES] 1099 Thompson, H., Hollander, D., Layman, A., Bray, T., and R. 1100 Tobin, "Namespaces in XML 1.0 (Third Edition)", World Wide 1101 Web Consortium Recommendation REC-xml-names-20091208, 1102 December 2009, 1103 . 1105 Appendix A. Registration Template 1107 A.1. Namespace ID 1109 Requested of IANA (formal) or assigned by IANA (informal). 1111 A.2. Version 1113 The version of the registration, starting with 1 and incrementing by 1114 1 with each new version. 1116 A.3. Date 1118 The date when the registration is requested of IANA, using the format 1119 YYYY-MM-DD. 1121 A.4. Registrant 1123 The person or organization that has registered the NID, including the 1124 following information: 1126 o The name and address of the registering organization. 1128 o The name and contact information (email, phone number, and/or 1129 postal address) of the designated contact person. 1131 A.5. Purpose 1133 Described under Section 7.1 of this document. 1135 A.6. Syntax 1137 Described under Section 7.2 of this document. Unless the 1138 registration explicitly says otherwise, use of p-, q-, and/or 1139 f-components is not allowed for this namespace. 1141 A.7. Assignment 1143 Described under Section 7.3 of this document. 1145 A.8. Resolution 1147 Described under Section 7.5 of this document. 1149 A.9. Documentation 1151 A pointer to an RFC, a specification published by another standards 1152 development organization, or another stable document that provides 1153 further information about the namespace. 1155 A.10. Revision Information 1157 (Applicable only when earlier registrations have been revised.) 1159 Description of changes from prior version(s). 1161 Appendix B. Changes from RFC 2141 1163 This document makes the following substantive changes from [RFC2141]: 1165 o Allows p-components, q-components, and f-components. 1167 o Disallows "-" at the end of a NID. 1169 o Allows the "~" and "&" characters in an NSS. 1171 o Formally registers 'urn' as a URI scheme. 1173 Appendix C. Changes from RFC 3406 1175 This document makes the following substantive changes from [RFC3406]: 1177 1. Relaxes the registration policy for formal namespaces from "IETF 1178 Review" to "Expert Review" as discussed in Section 8.1 and 1179 Section 9. 1181 2. Removes the category of experimental namespaces, consistent with 1182 [RFC6648]. 1184 3. Simplifies the registration template. 1186 In addition, some of the text has been updated to be consistent with 1187 the definition of Uniform Resource Identifiers (URIs) [RFC3986] and 1188 the processes for registering information with the IANA [RFC5226], as 1189 well as more modern guidance with regard to security issues [RFC3552] 1190 and identifier comparison [RFC6943]. 1192 Appendix D. Contributors 1194 RFC 2141, which provided the basis for the syntax portion of this 1195 document, was authored by Ryan Moats. 1197 RFC 3406, which provided the basis for the namespace portion of this 1198 document, was authored by Leslie Daigle, Dirk-Willem van Gulik, 1199 Renato Iannella, and Patrik Faltstrom. 1201 Their work is gratefully acknowledged. 1203 Appendix E. Acknowledgements 1205 Many thanks to Marc Blanchet, Leslie Daigle, Martin Duerst, Juha 1206 Hakala, Ted Hardie, Alfred Hoenes, Paul Jones, Barry Leiba, Sean 1207 Leonard, Larry Masinter, Keith Moore, Mark Nottingham, Julian 1208 Reschke, Lars Svensson, Dale Worley, and other participants in the 1209 URNBIS WG for their input. Alfred Hoenes in particular edited an 1210 earlier version of this document and served as co-chair of the URNBIS 1211 WG. 1213 Juha Hakala deserves special recognition for his dedication to 1214 successfully completing this work, as do Andrew Newton and Melinda 1215 Shore in their roles as working group co-chairs and Barry Leiba in 1216 his role as area director. 1218 Appendix F. Change log for versions of draft-ietf-urnbis-rfc2141bis-urn 1220 [[RFC Editor: please remove this appendix before publication.]] 1222 F.1. Changes from -08 to -09 1224 o Altered the text in Section 5 to reflect list discussions about 1225 the earlier phrasing. Also added DOI example and citation to that 1226 section. 1228 o Clarified the naming rules for formal namespaces and their 1229 relationship to ISO 3166, IDNA, etc., reserved strings. 1231 o Added an explicit statement about use of URNs in various protocols 1232 and contexts to Section 5. 1234 o Clarified that experimental namespace NIDs, which were explicitly 1235 not registered, are not valid URNs (in Section 6. 1237 o Transformed the partial production in Section 6.2 into valid ABNF. 1239 o Added more text about p-/q-/f-components and recommendations about 1240 use. 1242 o Added clarifying note about "?" within q-components and 1243 f-components. 1245 o Added explicit requirement that revisions of existing 1246 registrations document the changes and added a slot for that 1247 description to the template. 1249 o Many small editorial changes and adjustments including adding 1250 additional references and cross-references for clarification. 1252 o Inserted a placeholder for additional examples. 1254 F.2. Changes from -09 to -10 1256 o Several clarifying editorial changes, most suggested by Ted Hardie 1257 and Henry S. Thompson (some of them off-list). 1259 o Added a large number of placeholders that identify issues that 1260 require WG consideration and resolution (or WG delegation to the 1261 editors). 1263 Authors' Addresses 1265 Peter Saint-Andre 1266 &yet 1268 Email: peter@andyet.com 1269 URI: https://andyet.com/ 1271 John C Klensin 1272 1770 Massachusetts Ave, Ste 322 1273 Cambridge, MA 02140 1274 USA 1276 Phone: +1 617 245 1457 1277 Email: john-ietf@jck.com