idnits 2.17.1 draft-ietf-urnbis-rfc3406bis-urn-ns-reg-09.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (February 12, 2014) is 3725 days in the past. Is this intentional? Checking references for intended status: Best Current Practice ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-22) exists of draft-ietf-urnbis-rfc2141bis-urn-07 ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126) -- Obsolete informational reference (is this intentional?): RFC 2611 (Obsoleted by RFC 3406) -- Obsolete informational reference (is this intentional?): RFC 3406 (Obsoleted by RFC 8141) Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 3 comments (--). 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: 3406 (if approved) February 12, 2014 5 Intended status: Best Current Practice 6 Expires: August 16, 2014 8 Uniform Resource Name (URN) Namespace Definition Mechanisms 9 draft-ietf-urnbis-rfc3406bis-urn-ns-reg-09 11 Abstract 13 This document supplements the Uniform Resource Name (URN) syntax 14 specification by defining the concept of a URN namespace, as well as 15 mechanisms for defining and registering such namespaces. This 16 document obsoletes RFC 3406. 18 Status of This Memo 20 This Internet-Draft is submitted in full conformance with the 21 provisions of BCP 78 and BCP 79. 23 Internet-Drafts are working documents of the Internet Engineering 24 Task Force (IETF). Note that other groups may also distribute 25 working documents as Internet-Drafts. The list of current Internet- 26 Drafts is at http://datatracker.ietf.org/drafts/current/. 28 Internet-Drafts are draft documents valid for a maximum of six months 29 and may be updated, replaced, or obsoleted by other documents at any 30 time. It is inappropriate to use Internet-Drafts as reference 31 material or to cite them other than as "work in progress." 33 This Internet-Draft will expire on August 16, 2014. 35 Copyright Notice 37 Copyright (c) 2014 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents 42 (http://trustee.ietf.org/license-info) in effect on the date of 43 publication of this document. Please review these documents 44 carefully, as they describe your rights and restrictions with respect 45 to this document. Code Components extracted from this document must 46 include Simplified BSD License text as described in Section 4.e of 47 the Trust Legal Provisions and are provided without warranty as 48 described in the Simplified BSD License. 50 Table of Contents 52 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 53 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 54 3. What is a URN Namespace? . . . . . . . . . . . . . . . . . . 3 55 4. URN Namespace Types . . . . . . . . . . . . . . . . . . . . . 5 56 4.1. Formal Namespaces . . . . . . . . . . . . . . . . . . . . 5 57 4.2. Informal Namespaces . . . . . . . . . . . . . . . . . . . 6 58 5. Defining a URN Namespace . . . . . . . . . . . . . . . . . . 7 59 5.1. Purpose . . . . . . . . . . . . . . . . . . . . . . . . . 7 60 5.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 8 61 5.3. Assignment . . . . . . . . . . . . . . . . . . . . . . . 8 62 5.4. Security and Privacy . . . . . . . . . . . . . . . . . . 9 63 5.5. Resolution . . . . . . . . . . . . . . . . . . . . . . . 9 64 6. Registration Template . . . . . . . . . . . . . . . . . . . . 10 65 6.1. Namespace ID . . . . . . . . . . . . . . . . . . . . . . 10 66 6.2. Version . . . . . . . . . . . . . . . . . . . . . . . . . 10 67 6.3. Date . . . . . . . . . . . . . . . . . . . . . . . . . . 10 68 6.4. Registrant . . . . . . . . . . . . . . . . . . . . . . . 10 69 6.5. Purpose . . . . . . . . . . . . . . . . . . . . . . . . . 10 70 6.6. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 10 71 6.7. Assignment . . . . . . . . . . . . . . . . . . . . . . . 10 72 6.8. Resolution . . . . . . . . . . . . . . . . . . . . . . . 10 73 6.9. Documentation . . . . . . . . . . . . . . . . . . . . . . 11 74 7. Registering a URN Namespace . . . . . . . . . . . . . . . . . 11 75 7.1. Formal Namespaces . . . . . . . . . . . . . . . . . . . . 11 76 7.2. Informal Namespaces . . . . . . . . . . . . . . . . . . . 11 77 8. Guidelines for Designated Experts . . . . . . . . . . . . . . 12 78 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 79 10. Security and Privacy Considerations . . . . . . . . . . . . . 12 80 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 81 11.1. Normative References . . . . . . . . . . . . . . . . . . 12 82 11.2. Informative References . . . . . . . . . . . . . . . . . 13 83 Appendix A. Changes from RFC 3406 . . . . . . . . . . . . . . . 14 84 Appendix B. Contributors . . . . . . . . . . . . . . . . . . . . 14 85 Appendix C. Acknowledgements . . . . . . . . . . . . . . . . . . 14 86 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 14 88 1. Introduction 90 A Uniform Resource Name (URN) [I-D.ietf-urnbis-rfc2141bis-urn] is a 91 Uniform Resource Identifier (URI) [RFC3986] that is intended to serve 92 as a persistent, location-independent resource identifier. This 93 document supplements the Uniform Resource Name (URN) syntax 94 specification [I-D.ietf-urnbis-rfc2141bis-urn] by defining: 96 1. The concept of a URN namespace. 98 2. A mechanism for defining a URN namespace and associating it with 99 a public identifier (called a Namespace ID or "NID"). 101 3. Procedures for registering NIDs with the Internet Assigned 102 Numbers Authority (IANA). 104 Syntactically, the NID follows the 'urn' scheme name. For instance, 105 a URN in the 'example' namespace [RFC6963] might be of the form 106 "urn:example:foo". 108 This document rests on two key assumptions: 110 1. Assignment of a URN is a managed process. 112 A string that conforms to the URN syntax is not necessarily a 113 valid URN, because a URN needs to be assigned according to the 114 rules of a particular namespace (in terms of syntax, semantics, 115 and process). 117 2. The space of URN namespaces is itself managed. 119 A string in the namespace identifier slot of the URN syntax is 120 not necessarily a valid URN namespace identifier, because in 121 order to be valid a namespace needs to be defined and registered 122 in accordance with the rules of this document. 124 URN namespaces were originally defined in [RFC2611], which was 125 obsoleted by [RFC3406]. Based on experience with defining and 126 registering URN namespaces since that time, this document specifies 127 URN namespaces with the smallest reasonable set of changes from 128 [RFC3406], while at the same time simplifying the registration 129 process. This document obsoletes RFC 3406. 131 2. Terminology 133 Several important terms used in this document are defined in the URN 134 syntax specification [I-D.ietf-urnbis-rfc2141bis-urn]. 136 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 137 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 138 "OPTIONAL" in this document are to be interpreted as described in 139 [RFC2119]. 141 3. What is a URN Namespace? 143 A URN namespace is a collection of identifiers that are (1) unique, 144 (2) assigned in a consistent way, and (3) assigned according to a 145 common definition. 147 1. The "uniqueness" constraint means that an identifier within the 148 namespace is never assigned to more than one resource and never 149 reassigned to a different resource, even if the identifier itself 150 is deprecated or becomes obsolete. 152 2. The "consistent assignment" constraint means that an identifier 153 within the namespace is assigned by an organization or created in 154 accordance with a process or algorithm that is always followed. 156 3. The "common definition" constraint means that there are clear 157 definitions for the syntax of identifiers within the namespace 158 and the process of assigning or creating them. 160 A URN namespace is identified by a particular NID in order to ensure 161 the global uniqueness of URNs and, optionally, to provide a cue 162 regarding the structure of URNs assigned within a namespace. 164 With regard to global uniqueness, using different NIDs for different 165 collections of identifiers ensures that no two URNs will be the same 166 for different resources, since each collection is required to 167 uniquely assign each identifier. However, a single resource can have 168 more than one URN assigned to it for different purposes (e.g., some 169 numbers might be valid identifiers in two different identifier 170 systems, where the namespace identifier differentiates between the 171 resulting URNs). 173 With regard to the structure of URNs assigned within a namespace, the 174 development of an identifier structure (and thereby a collection of 175 identifiers) depends on the requirements of the community defining 176 the identifiers, how the identifiers will be assigned and used, etc. 177 These issues are beyond the scope of URN syntax and the general rules 178 for URN namespaces, because they are specific to the community 179 defining a namespace (e.g., the bibliographic and publishing 180 communities in the case of the 'ISBN' and 'ISSN' namespaces, or the 181 developers of extensions to the Extensible Messaging and Presence 182 Protocol in the case of the 'XMPP' namespace). 184 URN namespaces inherit certain rights and responsibilities by the 185 nature of URNs [I-D.ietf-urnbis-rfc2141bis-urn], e.g.: 187 1. They uphold the general principles of a well-managed URN 188 namespace by providing persistent identification of resources and 189 unique assignment of identifier strings. 191 2. They can be registered in global registration services. 193 4. URN Namespace Types 195 There are two types of URN namespace: formal and informal. These are 196 distinguished by the expected level of service, the information 197 needed to define the namespace, and the procedures for registration. 198 Because the majority of the namespaces registered so far have been 199 formal, this document concentrates on formal namespaces. 201 Note: [RFC3406] defined a third type of "experimental namespaces", 202 denoted by prefixing the namespace identifier with the string "X-". 203 Consistent with [RFC6648], this specification removes the 204 experimental category. Because experimental namespaces were never 205 registered, removing the experimental category has no impact on the 206 existing registries or future registration procedures. 208 4.1. Formal Namespaces 210 A formal namespace provides benefit to some subset of users on the 211 Internet (e.g., it would not make sense for a formal namespace to be 212 used only by a community or network that is not connected to the 213 Internet). For example, it would be inappropriate for a NID to 214 effectively force someone to use a proprietary network or service not 215 open to the general Internet user. The intent is that, while the 216 community of those who might actively use the names assigned within 217 that NID might be small, the potential use of identifiers within that 218 NID is open to any user on the Internet. Formal NIDs might be 219 appropriate when some aspects are not fully open. For example, a 220 namespace might make use of a fee-based, privately managed, or 221 proprietary registry for assignment of URNs in the namespace. 222 However, it might still benefit some Internet users if the associated 223 services have openly-published access protocols. 225 An organization that will assign URNs within a formal namespace ought 226 to meet the following criteria: 228 1. Organizational stability and the ability to maintain the URN 229 namespace for a long time; absent such evidence, it ought to be 230 clear how the namespace can remain viable if the organization can 231 no longer maintain the namespace. 233 2. Competency in name assignment. This will improve the likelihood 234 of persistence (e.g. to minimize the likelihood of conflicts). 236 3. Commitment to not reassigning existing names and to allowing old 237 names to continue to be valid, even if the owners or assignees of 238 those names are no longer members or customers of that 239 organization. With regard to URN resolution [RFC2276], this does 240 not mean that there needs to be resolution of such names, only 241 that the names will not resolve to false or stale information. 243 A formal namespace establishes a particular NID, subject to the 244 following constraints (above and beyond the syntax rules specified in 245 [I-D.ietf-urnbis-rfc2141bis-urn]): 247 1. It MUST NOT be an already-registered NID. 249 2. It MUST NOT start with "urn-" (which is reserved for informal 250 namespaces). 252 3. It MUST be more than two characters long. 254 4. It MUST NOT start with "aa-", where "aa" is any combination of 255 two ASCII letters. 257 5. It MUST NOT start with the string "xn--", which is reserved for 258 potential representation of DNS A-labels in the future [RFC5890]. 260 All two-letter combinations, and all two-letter combinations followed 261 by "-" and any sequence of valid NID characters, are reserved for 262 potential use as countrycode-based NIDs for eventual national 263 registrations of URN namespaces. The definition and scoping of rules 264 for allocation of responsibility for such countrycode-based 265 namespaces is beyond the scope of this document. 267 4.2. Informal Namespaces 269 Informal namespaces are full-fledged URN namespaces, with all the 270 associated rights and responsibilities. Informal namespaces differ 271 from formal namespaces in the process for assigning a NID: for an 272 informal namespace, the registrant does not designate the NID; 273 instead, IANA assigns a NID consisting of the string 'urn-' followed 274 by one or more digits (e.g., "urn-7") where the digits consist of the 275 next available number in the sequence of positive integers assigned 276 to informal namespaces. Thus the syntax of an informal namespace is: 278 "urn-" 280 The only restrictions on are that it (1) consist strictly of 281 ASCII digits and (2) not cause the NID to exceed the length 282 limitations defined in the URN syntax specification 283 [I-D.ietf-urnbis-rfc2141bis-urn]. 285 5. Defining a URN Namespace 287 The definition of a formal namespace ought to pay particular 288 attention to: 290 1. The purpose of the namespace. 292 2. The syntax of URNs assigned within the namespace. 294 3. The process for assigning URNs within the namespace. 296 4. The security implications of assigning and using the assigned 297 URNs. 299 5. Optionally, the process for resolving URNs issued within the 300 namepace. 302 The following sections explain these matters in greater detail. For 303 convenience, a template for defining and registering a URN namespace 304 is provided under Section 6. This information can be especially 305 helpful to entities that wish to request assignment of a URN in a 306 namespace and to entities that wish to provide URN resolution for a 307 namespace. 309 5.1. Purpose 311 The "Purpose" section of the template describes matters such as: 313 1. The kinds of resources identified by URNs assigned within the 314 namespace. 316 2. Why it is preferable to use URNs rather than some other 317 technology (e.g., URIs) and why no existing URN namespace is a 318 good fit. 320 3. The kinds of software applications that can use or resolve the 321 assigned URNs (e.g., by differentiating among disparate 322 namespaces, identifying resources in a persistent fashion, or 323 meaningfully resolving and accessing services associated with the 324 namespace). 326 4. The scope of the namespace (public vs. private, global vs. local 327 to a particular organization, nation, or industry). For example, 328 a namespace claiming to deal in "national identification numbers" 329 ought to have a global scope and address all identity number 330 structures, whereas a URN scheme for a particular national 331 identification number system would need to handle only the 332 structure for that nation's identity numbers. 334 5. How the intended community (and the Internet community at large) 335 will benefit from using or resolving the assigned URNs. 337 5.2. Syntax 339 The "Syntax" section of the template describes: 341 1. A description of the structure of URNs within the namespace, in 342 conformance with the fundamental URN syntax 343 [I-D.ietf-urnbis-rfc2141bis-urn]. The structure might be 344 described in terms of a formal definition (e.g., using Augmented 345 BNF for Syntax Specifications (ABNF) as specified in [RFC5234]), 346 an algorithm for generating conformant URNs, a regular expression 347 for parsing the identifier into components, or by explaining that 348 the structure is opaque. 350 2. Any special character encoding rules for assigned URNs (e.g., 351 which character ought to always be used for single-quotes). 353 3. Rules for determining equivalence between two identifiers in the 354 namespace. Such rules ought to always have the effect of 355 eliminating false negatives that might otherwise result from 356 comparison. If it is appropriate and helpful, reference can be 357 made to the equivalence rules defined in the URI specification 358 [RFC3986]. Examples of equivalence rules include equivalence 359 between uppercase and lowercase characters in the Namespace 360 Specific String, between hyphenated and non-hyphenated groupings 361 in the identifier string, or between single-quotes and double- 362 quotes. (Note that these are not normative statements for any 363 kind of best practice related to handling of equivalences between 364 characters in general; they are statements limited to one 365 particular namespace only.) 367 4. Any special considerations necessary for conforming with the URN 368 syntax. This is particularly applicable in the case of legacy 369 naming systems that are used in the context of URNs. For 370 example, if a namespace is used in contexts other than URNs, it 371 might make use of characters that are reserved in the URN syntax. 372 This section ought to note any such characters, and outline 373 necessary mappings to conform to URN syntax. Normally, this will 374 be handled by percent-encoding the character as specified in the 375 URI specification [RFC3986]. 377 5.3. Assignment 379 The "Assignment" section of the template describes matters such as: 381 1. Mechanisms or authorities for assigning URNs to resources. It 382 ought to make clear whether assignment is completely open (e.g., 383 following a particular algorithm), completely closed (e.g., for a 384 private organization), or limited in various ways (e.g., 385 delegated to authorities recognized by a particular 386 organization); if limited, it ought to explain how to become an 387 assigner of identifiers or how to request assignemtn of 388 identifers from existing assignment authorities. 390 2. Methods for ensuring that URNs within the namespace are unique. 391 For example, identifiers might be assigned sequentially or in 392 accordance with some well-defined process by a single authority, 393 assignment might be partitioned among delegated authorities that 394 are individually responsible for respecting uniqueness rules, or 395 URNs might be created independently following an algorithm that 396 itself guarantees uniqueness. 398 5.4. Security and Privacy 400 The "Security" section of the template describes any potential issues 401 related to security and privacy with regard to assignment, use, and 402 resolution of identifiers within the namespace. Examples of such 403 issues include the consequences of producing false negatives and 404 false positives during comparison for equivalence (see also 405 [RFC6943]), leakage of private information when identifiers are 406 communicated on the public Internet, the potential for directory 407 harvesting, and various issues discussed in the guidelines for 408 security considerations in RFCs [RFC3552] and the privacy 409 considerations for Internet protocols [RFC6973]. 411 5.5. Resolution 413 The "Resolution" section specifies the rules for resolution of URNs 414 assigned within the namespace. If such URNs are intended to be 415 resolvable, the namespace needs to be registered in a Resolution 416 Discovery System (RDS, see [RFC2276]) such as DDDS. Resolution then 417 proceeds according to standard URI resolution processes, as well as 418 the mechanisms of the RDS. This section ought to lists the 419 requirements for becoming a recognized resolver of URNs in the 420 relevant namespace (and being so listed in the RDS registry). 421 Answers might include, but are not limited to: 423 1. The namespace is not listed with an RDS; therefore this section 424 is not applicable. 426 2. Resolution mirroring is completely open, with a mechanism for 427 updating an appropriate RDS. 429 3. Resolution is controlled by entities to which assignment has been 430 delegated. 432 6. Registration Template 434 6.1. Namespace ID 436 Requested of IANA (formal) or assigned by IANA (informal). 438 6.2. Version 440 The version of the registration, starting with 1 and incrementing by 441 1 with each new version. 443 6.3. Date 445 The date when the registration is requested of IANA, using the format 446 YYYY-MM-DD. 448 6.4. Registrant 450 The person or organization that has registered the NID, including the 451 following information: 453 o The name and address of the registering organization. 455 o The name and contact information (email, phone number, and/or 456 postal address) of the designated contact person. 458 6.5. Purpose 460 Described under Section 5.1 of this document. 462 6.6. Syntax 464 Described under Section 5.2 of this document. 466 6.7. Assignment 468 Described under Section 5.3 of this document. 470 6.8. Resolution 472 Described under Section 5.5 of this document. 474 6.9. Documentation 476 A pointer to an RFC, a specification published by another standards 477 development organization, or another stable document that provides 478 further information about the namespace. 480 7. Registering a URN Namespace 482 7.1. Formal Namespaces 484 The registration policy for formal namespaces is Expert Review as 485 defined in the "IANA Considerations" document [RFC5226]. The key 486 steps for registration of a formal namespace are: 488 1. Fill out the namespace registration template (see Section 6). 489 This can be done as part of an Internet-Draft or a specification 490 in another series, although that is not necessary. 492 2. Send the completed template to the urn-nid@ietf.org discussion 493 list for review. 495 3. If necessary to address comments received, repeat steps 1 and 2. 497 4. If the designated experts approve the request, the IANA will 498 register the requested NID. 500 A formal namespace registration can be revised by updating the 501 registration template, following the same steps outlined above for 502 new registrations. A revised registration should making special note 503 of any relevant changes in the underlying technologies or namespace 504 management processes. 506 7.2. Informal Namespaces 508 The registration policy for informal namespaces is First Come First 509 Served [RFC5226]. The key steps for registration of an informal 510 namespace are: 512 1. Write a completed namespace definition template (see Section 6). 514 2. Send it to the urn-nid@ietf.org discussion list for feedback. 516 3. Once the review period has expired, send the final template to 517 IANA (via the iana@iana.org email address). 519 An informal namespace registration can be revised by updating the 520 registration template, following the same steps outlined above for 521 new registrations. 523 8. Guidelines for Designated Experts 525 Experience to date with NID registration requests has shown that 526 registrants sometimes do not initially understand some of the 527 subtleties of URN namespaces, and that defining the namespace in the 528 form of a specification enables the registrants to clearly formulate 529 their "contract" with the intended user community. Therefore, 530 although the registration policy for formal namespaces is Expert 531 Review and a stable specification is not strictly required, the 532 designated experts for NID registration requests ought to encourage 533 applicants to provide a stable specification documenting the 534 namespace definition. 536 Naming can be difficult and contentious; the designated experts and 537 applicants are strongly encouraged to work together in a spirit of 538 good faith and mutual understanding to achieve rough consensus on 539 progressing registrations through the process. They are also 540 encouraged to bring additional expertise into the discussion if that 541 would be helpful in adding perspective or otherwise resolving issues. 543 9. IANA Considerations 545 This document outlines the processes for registering URN namespaces, 546 and has implications for the IANA in terms of registries to be 547 maintained. In all cases, the IANA ought to assign the appropriate 548 NID (formal or informal) once the procedures outlined in this 549 document have been completed. 551 10. Security and Privacy Considerations 553 This document largely focuses on providing mechanisms for the 554 declaration of public information. Nominally, these declarations 555 will be of relatively low security profile, however there is always 556 the danger of "spoofing" and providing misinformation. Information 557 in these declarations ought to be taken as advisory. 559 The definition of a URN namespace needs to account for potential 560 security and privacy issues related to assignment, use, and 561 resolution of identifiers within the namespace. 563 11. References 565 11.1. Normative References 567 [I-D.ietf-urnbis-rfc2141bis-urn] 568 Saint-Andre, P., Ed., "Uniform Resource Name (URN) 569 Syntax", draft-ietf-urnbis-rfc2141bis-urn-07 (work in 570 progress), January 2014. 572 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 573 Requirement Levels", BCP 14, RFC 2119, March 1997. 575 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 576 Resource Identifier (URI): Generic Syntax", STD 66, RFC 577 3986, January 2005. 579 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 580 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 581 May 2008. 583 11.2. Informative References 585 [RFC2276] Sollins, K., "Architectural Principles of Uniform Resource 586 Name Resolution", RFC 2276, January 1998. 588 [RFC2611] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom, 589 "URN Namespace Definition Mechanisms", BCP 33, RFC 2611, 590 June 1999. 592 [RFC3406] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom, 593 "Uniform Resource Names (URN) Namespace Definition 594 Mechanisms", BCP 66, RFC 3406, October 2002. 596 [RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC 597 Text on Security Considerations", BCP 72, RFC 3552, July 598 2003. 600 [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax 601 Specifications: ABNF", STD 68, RFC 5234, January 2008. 603 [RFC5890] Klensin, J., "Internationalized Domain Names for 604 Applications (IDNA): Definitions and Document Framework", 605 RFC 5890, August 2010. 607 [RFC6648] Saint-Andre, P., Crocker, D., and M. Nottingham, 608 "Deprecating the "X-" Prefix and Similar Constructs in 609 Application Protocols", BCP 178, RFC 6648, June 2012. 611 [RFC6943] Thaler, D., "Issues in Identifier Comparison for Security 612 Purposes", RFC 6943, May 2013. 614 [RFC6963] Saint-Andre, P., "A Uniform Resource Name (URN) Namespace 615 for Examples", BCP 183, RFC 6963, May 2013. 617 [RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., 618 Morris, J., Hansen, M., and R. Smith, "Privacy 619 Considerations for Internet Protocols", RFC 6973, July 620 2013. 622 Appendix A. Changes from RFC 3406 624 This document makes the following substantive changes from [RFC3406]: 626 1. Relaxes the registration policy for formal namespaces from "IETF 627 Review" to "Expert Review" [RFC5226]. 629 2. Removes the category of experimental namespaces, consistent with 630 [RFC6648]. 632 3. Simplifies the registration template. 634 In addition, some of the text has been updated to be consistent with 635 the definition of Uniform Resource Identifiers (URIs) [RFC3986] and 636 the processes for registering information with the IANA [RFC5226], as 637 well as more modern guidance with regard to security issues [RFC3552] 638 and identifier comparison [RFC6943]. 640 Appendix B. Contributors 642 RFC 3406, which provided the basis for this document, was authored by 643 Leslie Daigle, Dirk-Willem van Gulik, Renato Iannella, and Patrik 644 Faltstrom. Their work is gratefully acknowledged. 646 Appendix C. Acknowledgements 648 Thanks to Marc Blanchet, Juha Hakala, Paul Jones, John Klensin, and 649 Barry Leiba for their input. 651 Author's Address 653 Peter Saint-Andre 654 &yet 656 Email: ietf@stpeter.im