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'I-D.appsawg-media-type-suffix-regs' == Outdated reference: draft-ietf-appsawg-mime-default-charset has been published as RFC 6657 ** Obsolete normative reference: RFC 3023 (Obsoleted by RFC 7303) ** Obsolete normative reference: RFC 3979 (Obsoleted by RFC 8179) ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126) == Outdated reference: draft-ietf-appsawg-xdash has been published as RFC 6648 -- Obsolete informational reference (is this intentional?): RFC 2048 (Obsoleted by RFC 4288, RFC 4289) -- Obsolete informational reference (is this intentional?): RFC 2616 (Obsoleted by RFC 7230, RFC 7231, RFC 7232, RFC 7233, RFC 7234, RFC 7235) -- Obsolete informational reference (is this intentional?): RFC 4288 (Obsoleted by RFC 6838) -- Obsolete informational reference (is this intentional?): RFC 4844 (Obsoleted by RFC 8729) Summary: 3 errors (**), 0 flaws (~~), 4 warnings (==), 9 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group N. Freed 3 Internet-Draft Oracle 4 Obsoletes: 4288 (if approved) J. Klensin 5 Intended status: BCP 6 Expires: November 17, 2012 T. Hansen 7 AT&T Laboratories 8 May 16, 2012 10 Media Type Specifications and Registration Procedures 11 draft-ietf-appsawg-media-type-regs-08 13 Abstract 15 This document defines procedures for the specification and 16 registration of media types for use in HTTP, MIME and other Internet 17 protocols. 19 Status of this Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at http://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on November 17, 2012. 36 Copyright Notice 38 Copyright (c) 2012 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (http://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 54 1.1. Historical Note . . . . . . . . . . . . . . . . . . . . . 4 55 1.2. Conventions Used in This Document . . . . . . . . . . . . 4 56 2. Media Type Registration Preliminaries . . . . . . . . . . . . 5 57 3. Registration Trees and Subtype Names . . . . . . . . . . . . . 5 58 3.1. Standards Tree . . . . . . . . . . . . . . . . . . . . . . 5 59 3.2. Vendor Tree . . . . . . . . . . . . . . . . . . . . . . . 6 60 3.3. Personal or Vanity Tree . . . . . . . . . . . . . . . . . 7 61 3.4. Unregistered x. Tree . . . . . . . . . . . . . . . . . . . 7 62 3.5. Additional Registration Trees . . . . . . . . . . . . . . 8 63 4. Registration Requirements . . . . . . . . . . . . . . . . . . 8 64 4.1. Functionality Requirement . . . . . . . . . . . . . . . . 8 65 4.2. Naming Requirements . . . . . . . . . . . . . . . . . . . 9 66 4.2.1. Text Media Types . . . . . . . . . . . . . . . . . . . 10 67 4.2.2. Image Media Types . . . . . . . . . . . . . . . . . . 11 68 4.2.3. Audio Media Types . . . . . . . . . . . . . . . . . . 11 69 4.2.4. Video Media Types . . . . . . . . . . . . . . . . . . 11 70 4.2.5. Application Media Types . . . . . . . . . . . . . . . 11 71 4.2.6. Multipart and Message Media Types . . . . . . . . . . 12 72 4.2.7. Additional Top-level Types . . . . . . . . . . . . . . 12 73 4.2.8. Structured Syntax Name Suffixes . . . . . . . . . . . 12 74 4.2.9. Deprecated Aliases . . . . . . . . . . . . . . . . . . 13 75 4.3. Parameter Requirements . . . . . . . . . . . . . . . . . . 13 76 4.4. Canonicalization and Format Requirements . . . . . . . . . 14 77 4.5. Interchange Recommendations . . . . . . . . . . . . . . . 15 78 4.6. Security Requirements . . . . . . . . . . . . . . . . . . 15 79 4.7. Requirements specific to XML media types . . . . . . . . . 16 80 4.8. Encoding Requirements . . . . . . . . . . . . . . . . . . 17 81 4.9. Usage and Implementation Non-requirements . . . . . . . . 17 82 4.10. Publication Requirements . . . . . . . . . . . . . . . . . 18 83 4.11. Fragment Identifier Requirements . . . . . . . . . . . . . 19 84 4.12. Additional Information . . . . . . . . . . . . . . . . . . 19 85 5. Media Type Registration Procedures . . . . . . . . . . . . . . 19 86 5.1. Preliminary Community Review . . . . . . . . . . . . . . . 20 87 5.2. Submit request to IANA . . . . . . . . . . . . . . . . . . 20 88 5.2.1. Provisional Registrations . . . . . . . . . . . . . . 20 89 5.3. Review and Approval . . . . . . . . . . . . . . . . . . . 21 90 5.4. Comments on Media Type Registrations . . . . . . . . . . . 21 91 5.5. Location of Registered Media Type List . . . . . . . . . . 21 92 5.6. Change Procedures . . . . . . . . . . . . . . . . . . . . 22 93 5.7. Registration Template . . . . . . . . . . . . . . . . . . 23 94 6. Structured Syntax Suffix Registration Procedures . . . . . . . 24 95 6.1. Change Procedures . . . . . . . . . . . . . . . . . . . . 25 96 6.2. Structured Syntax Suffix Registration Template . . . . . . 25 97 7. Security Considerations . . . . . . . . . . . . . . . . . . . 26 98 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26 99 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 27 100 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 27 101 10.1. Normative References . . . . . . . . . . . . . . . . . . . 27 102 10.2. Informative References . . . . . . . . . . . . . . . . . . 28 103 Appendix A. Grandfathered Media Types . . . . . . . . . . . . . . 29 104 Appendix B. Changes Since RFC 4288 . . . . . . . . . . . . . . . 29 105 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 31 107 1. Introduction 109 Recent Internet protocols have been carefully designed to be easily 110 extensible in certain areas. In particular, many protocols, 111 including but not limited to HTTP [RFC2616] and MIME [RFC2045], are 112 capable of carrying arbitrary labeled content. A mechanism is needed 113 to label such content and a registration process is needed for these 114 labels, so that that the set of such values are defined in a 115 reasonably orderly, well-specified, and public manner. 117 This document defines media type specification and registration 118 procedures (Section 5) that use the Internet Assigned Numbers 119 Authority (IANA) as a central registry. 121 1.1. Historical Note 123 The media type registration process was initially defined for 124 registering media types for use in the context of the asynchronous 125 Internet mail environment. In this mail environment there is a need 126 to limit the number of possible media types, to increase the 127 likelihood of interoperability when the capabilities of the remote 128 mail system are not known. As media types are used in new 129 environments in which the proliferation of media types is not a 130 hindrance to interoperability, the original procedure proved 131 excessively restrictive and had to be generalized. This was 132 initially done in [RFC2048], but the procedure defined there was 133 still part of the MIME document set. The media type specification 134 and registration procedure has now been moved to this separate 135 document, to make it clear that it is independent of MIME. 137 It may be desirable to restrict the use of media types to specific 138 environments or to prohibit their use in other environments. This 139 revision incorporates such restrictions into media type registrations 140 in a systematic way. See Section 4.9 for additional discussion. 142 1.2. Conventions Used in This Document 144 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 145 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 146 document are to be interpreted as described in [RFC2119] when they 147 appear in ALL CAPS. These words may also appear in this document in 148 lower case as plain English words, absent their normative meanings. 150 This specification makes use of the Augmented Backus-Naur Form (ABNF) 151 [RFC5234] notation, including the core rules defined in Appendix A of 152 that document. 154 2. Media Type Registration Preliminaries 156 Registration of a new media type or types starts with the 157 construction of a registration proposal. Registration may occur 158 within several different registration trees that have different 159 requirements, as discussed below. In general, a new registration 160 proposal is circulated and reviewed in a fashion appropriate to the 161 tree involved. The media type is then registered if the proposal is 162 acceptable. The following sections describe the requirements and 163 procedures used for each of the different registration trees. 165 3. Registration Trees and Subtype Names 167 In order to increase the efficiency and flexibility of the 168 registration process, different structures of subtype names can be 169 registered to accommodate the different natural requirements for, 170 e.g., a subtype that will be recommended for wide support and 171 implementation by the Internet community, or a subtype that is used 172 to move files associated with proprietary software. The following 173 subsections define registration "trees" that are distinguished by the 174 use of faceted names, e.g., names of the form 175 "tree.subtree...subtype". Note that some media types defined prior 176 to this document do not conform to the naming conventions described 177 below. See Appendix A for a discussion of them. 179 3.1. Standards Tree 181 The standards tree is intended for types of general interest to the 182 Internet community. Registrations in the standards tree MUST be 183 either: 185 1. in the case of registrations in IETF specifications, approved 186 directly by the IESG, or 188 2. registered by a recognized standards body using the 189 "Specification Required" IANA registration policy [RFC5226] 190 (which implies Expert Review). 192 The first procedure is used for registering registrations from IETF 193 Consensus documents, or in rare cases when registering a 194 grandfathered (see Appendix A) and/or otherwise incomplete 195 registration is in the interest of the Internet community. 197 In the second case the IESG makes a one time decision on whether the 198 registration submitter represents a recognized standards body; after 199 that, a Media Types Reviewer (Designated Expert or a group of 200 Designated Experts) performs the Expert Review as specified in this 201 document. Subsequent submissions from the same source do not involve 202 the IESG. 204 In the case of registration for the IETF itself, the registration 205 proposal MUST be published as an RFC. When the RFC is in the IETF 206 stream it is an IETF Consensus RFC [RFC4844] , which can be on the 207 Standards Track, a BCP, Informational, or Experimental. 208 Registrations published in non-IETF RFC streams are also allowed, and 209 require IESG approval. 211 In the case of registrations for other recognized standards bodies, 212 the format MUST be described by a formal standards specification 213 produced by that body. 215 A standards-tree registration can be either in a standalone 216 "registration only" RFC or incorporated into a more general 217 specification of some sort. 219 Media types in the standards tree MUST NOT have faceted names, unless 220 they are grandfathered in using the process described in Appendix A. 222 The "owner" of a media type registered in the standards tree is 223 assumed to be the standards body itself. Modification or alteration 224 of the specification uses the same level of processing (e.g., a 225 registration submitted on Standards Track can be revised in another 226 Standards Track RFC, but cannot be revised in an Informational RFC) 227 required for the initial registration. 229 Standards-tree registrations from recognized standards bodies may be 230 submitted directly to the IANA, where they will undergo Expert Review 231 [RFC5226] prior to approval. In this case, the Expert Reviewer(s) 232 will, among other things, ensure that the required specification 233 provides adequate documentation. 235 3.2. Vendor Tree 237 The vendor tree is used for media types associated with publicly 238 available products. "Vendor" and "producer" are construed very 239 broadly in this context and are considered equivalent. Note that 240 industry consortia as well as non-commercial entities that do not 241 qualify as recognized standards bodies can quite appropriately 242 register media types in the vendor tree. 244 A registration may be placed in the vendor tree by anyone who needs 245 to interchange files associated with some product or set of products. 246 However, the registration properly belongs to the vendor or 247 organization producing the software that employs the type being 248 registered, and that vendor or organization can at any time elect to 249 assert ownership of a registration done by a third party in order to 250 correct or update it. See Section 5.6 for additional information. 252 When a third party registers a type on behalf of someone else both 253 entities SHOULD be noted in the Change Controller field in the 254 registration. One possible format for this would be "Foo, on behalf 255 of Bar". 257 Registrations in the vendor tree will be distinguished by the leading 258 facet "vnd.". That may be followed, at the discretion of the 259 registrant, by either a media subtype name from a well-known producer 260 (e.g., "vnd.mudpie") or by an IANA-approved designation of the 261 producer's name that is followed by a media type or product 262 designation (e.g., vnd.bigcompany.funnypictures). 264 While public exposure and review of media types to be registered in 265 the vendor tree is not required, using the media-types@iana.org 266 mailing list for review is encouraged to improve the quality of those 267 specifications. Registrations in the vendor tree may be submitted 268 directly to the IANA, where they will undergo Expert Review [RFC5226] 269 prior to approval. 271 3.3. Personal or Vanity Tree 273 Registrations for media types created experimentally or as part of 274 products that are not distributed commercially may be registered in 275 the personal or vanity tree. The registrations are distinguished by 276 the leading facet "prs.". 278 The owner of "personal" registrations and associated specifications 279 is the person or entity making the registration, or one to whom 280 responsibility has been transferred as described below. 282 While public exposure and review of media types to be registered in 283 the personal tree is not required, using the media-types@iana.org 284 mailing list (see Section 5.1) for review is encouraged to improve 285 the quality of those specifications. Registrations in the personal 286 tree may be submitted directly to the IANA, where they will undergo 287 Expert Review [RFC5226] prior to approval. 289 3.4. Unregistered x. Tree 291 Subtype names with "x." as the first facet may be used for types 292 intended exclusively for use in private, local environments. Types 293 in this tree cannot be registered and are intended for use only with 294 the active agreement of the parties exchanging them. 296 However, with the simplified registration procedures described above 297 for vendor and personal trees, it should rarely, if ever, be 298 necessary to use unregistered types. Therefore, use of types in the 299 "x." tree is strongly discouraged. 301 Note that types with names beginning with "x-" are no longer 302 considered to members of this tree (see [I-D.ietf-appsawg-xdash]). 303 Also note that if a generally useful and widely deployed type 304 incorrectly ends up with an "x-" name prefix, it MAY be registered 305 using its current name in an alternate tree by following the 306 procedure defined in Appendix A. 308 3.5. Additional Registration Trees 310 From time to time and as required by the community, new top-level 311 registration trees may be created by IETF Standards Action. It is 312 explicitly assumed that these trees may be created for external 313 registration and management by well-known permanent bodies; for 314 example, scientific societies may register media types specific to 315 the sciences they cover. In general, the quality of review of 316 specifications for one of these additional registration trees is 317 expected to be equivalent to registrations in the standards tree by a 318 recognized Standards Development Organization. When the IETF 319 performs such review, it needs to consider the greater expertise of 320 the requesting body with respect to the subject media type. 322 4. Registration Requirements 324 Media type registrations are all expected to conform to various 325 requirements laid out in the following sections. Note that 326 requirement specifics sometimes vary depending on the registration 327 tree, again as detailed in the following sections. 329 4.1. Functionality Requirement 331 Media types MUST function as actual media formats. Registration of 332 things that are better thought of as a transfer encoding, as a 333 charset, or as a collection of separate entities of another type, is 334 not allowed. For example, although applications exist to decode the 335 base64 transfer encoding [RFC2045], base64 cannot be registered as a 336 media type. 338 This requirement applies regardless of the registration tree 339 involved. 341 4.2. Naming Requirements 343 All registered media types MUST be assigned top-level type and 344 subtype names. The combination of these names serves to uniquely 345 identify the media type, and the subtype name facet (or the absence 346 of one) identifies the registration tree. Both top-level type and 347 subtype names are case-insensitive. 349 Type and subtype names MUST conform to the following ABNF: 351 type-name = restricted-name 352 subtype-name = restricted-name 354 restricted-name = restricted-name-first *126restricted-name-chars 355 restricted-name-first = ALPHA / DIGIT 356 restricted-name-chars = ALPHA / DIGIT / "!" / "#" / 357 "$" / "&" / "-" / "^" / "_" 358 restricted-name-chars =/ "." ; Characters before first dot always 359 ; specify a facet name 360 restricted-name-chars =/ "+" ; Characters after last plus always 361 ; specify a structured syntax suffix 363 Note that this syntax is somewhat more restrictive than what is 364 allowed by the ABNF in section 5.1 of [RFC2045] or section 4.2 of 365 [RFC4288]. Also note that while this syntax allows names of up to 366 127 characters, implementation limits may make such long names 367 problematic. For this reason the components of names SHOULD be 368 limited to 64 characters. 370 Although the name syntax treats "." as equivalent to any other 371 character, characters before any initial "." always specify the 372 registration facet. Note that this means that facet-less standards 373 tree registrations cannot use periods in the subtype name. 375 Similarly, "+" is used in subtype names to introduce a structured 376 syntax specifier suffix. Structured syntax suffix requirements are 377 specified in Section 4.2.8. 379 While it is possible for a given media type to be assigned additional 380 names, the use of different names to identify the same media type is 381 discouraged. 383 These requirements apply regardless of the registration tree 384 involved. 386 The choice of top-level type MUST take into account the nature of 387 media type involved. New subtypes of top-level types MUST conform to 388 the restrictions of the top-level type, if any. The following 389 sections describe each of the initial set of top-level types and 390 their associated restrictions. Additionally, various protocols, 391 including but not limited to HTTP and MIME, MAY impose additional 392 restrictions on the media types they can transport. (See [RFC2046] 393 for additional information on the restrictions MIME imposes.) 395 4.2.1. Text Media Types 397 The "text" top-level type is intended for sending material that is 398 principally textual in form. 400 Many subtypes of text, notably including the subtype "text/plain", 401 which is a generic subtype for plain text defined in [RFC2046], 402 define a "charset" parameter. If a "charset" parameter is defined 403 for a particular subtype of text, it MUST be used to specify a 404 charset name defined in accordance to the procedures laid out in 405 [RFC2978]. 407 As specified in [I-D.ietf-appsawg-mime-default-charset], a "charset" 408 parameter SHOULD NOT be specified when charset information is 409 transported inside the payload (e.g., as in "text/xml"). 411 If a "charset" parameter is specified, it SHOULD be a required 412 parameter, eliminating the options of specifying a default value. If 413 there is a strong reason for the parameter to be optional despite 414 this advice, each subtype MAY specify its own default value, or 415 alternately, it MAY specify that there is no default value. Finally, 416 the "UTF-8" charset [RFC3629] SHOULD be selected as the default. See 417 [I-D.ietf-appsawg-mime-default-charset] for additional information on 418 the use of "charset" parameters in conjunction with subtypes of text. 420 Regardless of what approach is chosen, all text/* registrations MUST 421 clearly specify how the charset is determined; relying on the US- 422 ASCII default defined in Section 4.1.2 of [RFC2046] is no longer 423 permitted. If explanatory text is needed this SHOULD be placed in 424 the additional information section of the registration. 426 Plain text does not provide for or allow formatting commands, font 427 attribute specifications, processing instructions, interpretation 428 directives, or content markup. Plain text is seen simply as a linear 429 sequence of characters, possibly interrupted by line breaks or page 430 breaks. Plain text MAY allow the stacking of several characters in 431 the same position in the text. Plain text in scripts like Arabic and 432 Hebrew may also include facilities that allow the arbitrary mixing of 433 text segments with different writing directions. 435 Beyond plain text, there are many formats for representing what might 436 be known as "rich text". An interesting characteristic of many such 437 representations is that they are to some extent readable even without 438 the software that interprets them. It is useful to distinguish them, 439 at the highest level, from such unreadable data as images, audio, or 440 text represented in an unreadable form. In the absence of 441 appropriate interpretation software, it is reasonable to present 442 subtypes of "text" to the user, while it is not reasonable to do so 443 with most non-textual data. Such formatted textual data can be 444 represented using subtypes of "text". 446 4.2.2. Image Media Types 448 A top-level type of "image" indicates that the content specifies one 449 or more individual images. The subtype names the specific image 450 format. 452 4.2.3. Audio Media Types 454 A top-level type of "audio" indicates that the content contains audio 455 data. The subtype names the specific audio format. 457 4.2.4. Video Media Types 459 A top-level type of "video" indicates that the content specifies a 460 time-varying-picture image, possibly with color and coordinated 461 sound. The term 'video' is used in its most generic sense, rather 462 than with reference to any particular technology or format, and is 463 not meant to preclude subtypes such as animated drawings encoded 464 compactly. 466 Note that although in general the mixing of multiple kinds media in a 467 single body is discouraged [RFC2046], it is recognized that many 468 video formats include a representation for synchronized audio and/or 469 text, and this is explicitly permitted for subtypes of "video". 471 4.2.5. Application Media Types 473 The "application" top-level type is to be used for discrete data that 474 do not fit under any of the other type names, and particularly for 475 data to be processed by some type of application program. This is 476 information that must be processed by an application before it is 477 viewable or usable by a user. Expected uses for the "application" 478 type name include but are not limited to file transfer, spreadsheets, 479 presentations, scheduling data, and languages for "active" 480 (computational) material. (The last, in particular, can pose 481 security problems that must be understood by implementors The 482 "application/postscript" media type registration in [RFC2046] 483 provides a good example of how to handle these issues.) 484 For example, a meeting scheduler might define a standard 485 representation for information about proposed meeting dates. An 486 intelligent user agent would use this information to conduct a dialog 487 with the user, and might then send additional material based on that 488 dialog. More generally, there have been several "active" languages 489 developed in which programs in a suitably specialized language are 490 transported to a remote location and automatically run in the 491 recipient's environment. Such applications may be defined as 492 subtypes of the "application" top-level type. 494 The subtype of "application" will often either be the name or include 495 part of the name of the application for which the data are intended. 496 This does not mean, however, that any application program name may 497 simply be used freely as a subtype of "application"; the subtype 498 needs to be registered. 500 4.2.6. Multipart and Message Media Types 502 Multipart and message are composite types, that is, they provide a 503 means of encapsulating zero or more objects, each one a separate 504 media type. 506 All subtypes of multipart and message MUST conform to the syntax 507 rules and other requirements specified in [RFC2046] and amended by 508 Section 3.5 of [RFC6532]. 510 4.2.7. Additional Top-level Types 512 In some cases a new media type may not "fit" under any currently 513 defined top-level type names. Such cases are expected to be quite 514 rare. However, if such a case does arise a new type name can be 515 defined to accommodate it. Such a definition MUST be done via 516 standards-track RFC; no other mechanism can be used to define 517 additional type name. 519 4.2.8. Structured Syntax Name Suffixes 521 [RFC3023] defined the first such augmentation to the media type 522 definition to additionally specify the underlying structure of that 523 media type. To quote: 525 This document also standardizes a convention (using the suffix 526 '+xml') for naming media types ... when those media types 527 represent XML MIME (Multipurpose Internet Mail Extensions) 528 entities. 530 That is, it specified a suffix (in that case, "+xml") to be appended 531 to the base subtype name. 533 Since this was published, the de facto practice has arisen for using 534 this suffix convention for other well-known structuring syntaxes. In 535 particular, media types have been registered with suffixes such as 536 "+der", "+fastinfoset" and "+json". This specification formalizes 537 this practice and sets up a registry for structured type name 538 suffixes. 540 The primary guideline for whether a structured type name suffix is 541 registrable is that it be described by a readily-available 542 description, preferably within a document published by an established 543 standards organization, and for which there's a reference that can be 544 used in a Normative References section of an RFC. 546 Media types that make use of a named structured syntax SHOULD use the 547 appropriate registered "+suffix" for that structured syntax when they 548 are registered. By the same token, media types MUST NOT be given 549 names incorporating suffixes for structured syntaxes they do not 550 actually employ. "+suffix" constructs for as-yet unregistered 551 structured syntaxes SHOULD NOT be used, given the possibility of 552 conflicts with future suffix definitions. 554 4.2.9. Deprecated Aliases 556 In some cases a single media type may have been widely deployed prior 557 to registration under multiple names. In such cases a preferred name 558 MUST be chosen for the media type and applications MUST use this to 559 be compliant with the type's registration. However, a list of 560 deprecated aliases the type is known by MAY be supplied as additional 561 information in order to assist applications in processing the media 562 type properly. 564 4.3. Parameter Requirements 566 Media types MAY elect to use one or more media type parameters, or 567 some parameters may be automatically made available to the media type 568 by virtue of being a subtype of a content type that defines a set of 569 parameters applicable to any of its subtypes. In either case, the 570 names, values, and meanings of any parameters MUST be fully specified 571 when a media type is registered in the standards tree, and SHOULD be 572 specified as completely as possible when media types are registered 573 in the vendor or personal trees. 575 Parameter names have the syntax as media type names and values: 577 parameter-name = restricted-name 579 Note that this syntax is somewhat more restrictive than what is 580 allowed by the ABNF in [RFC2045] and amended by [RFC2231]. 582 Parameter names are case-insensitive and no meaning is attached to 583 the order in which they appear. It is an error for a specific 584 parameter to be specified more than once. 586 There is no defined syntax for parameter values. Therefore 587 registrations MUST specify parameter value syntax. Additionally, 588 some transports impose restrictions on parameter value syntax, so 589 care needs be taken to limit the use of potentially problematic 590 syntaxes; e.g., pure binary valued parameters, while permitted in 591 some protocols, are best avoided. 593 New parameters SHOULD NOT be defined as a way to introduce new 594 functionality in types registered in the standards tree, although new 595 parameters MAY be added to convey additional information that does 596 not otherwise change existing functionality. An example of this 597 would be a "revision" parameter to indicate a revision level of an 598 external specification such as JPEG. Similar behavior is encouraged 599 for media types registered in the vendor or personal trees, but is 600 not required. 602 Changes to parameters (including the introduction of new ones) is 603 managed in the same manner as other changes to the media type; see 604 Section 5.6. 606 4.4. Canonicalization and Format Requirements 608 All registered media types MUST employ a single, canonical data 609 format, regardless of registration tree. 611 A permanent and readily available public specification of the format 612 for the media type MUST exist for all types registered in the 613 standards tree, and this specification MUST provide sufficient detail 614 so that interoperability between independent implementations using 615 the media type is possible. This specification MUST at a minimum be 616 referenced by, if it is not actually included in, the media type 617 registration proposal itself. 619 The specifications of format and processing particulars may or may 620 not be publicly available for media types registered in the vendor 621 and personal trees, and such registrations are explicitly permitted 622 to limit the information in the registration to which software and 623 version produce or process such media types. As such, references to 624 or inclusion of format specifications in registrations is encouraged 625 but not required. Note, however, that the public availability of a 626 meaningful specification will often make the difference between 627 simply having a name reserved so that there are no conflicts with 628 other uses and having the potential for other implementations of the 629 media type and useful interoperation with them. 631 Some media types involve the use of patented technology. The 632 registration of media types involving patented technology is 633 specifically permitted. However, the restrictions set forth in BCP 634 79 [RFC3979] and BCP 78 [RFC5378] on the use of patented technology 635 in IETF standards-track protocols must be respected when the 636 specification of a media type is part of a standards-track protocol. 637 In addition, other standards bodies making use of the standards tree 638 may have their own rules regarding intellectual property that must be 639 observed in their registrations. 641 IPR disclosures for registrations in the vendor and personal tree are 642 encouraged but not required. 644 4.5. Interchange Recommendations 646 Media types SHOULD interoperate across as many systems and 647 applications as possible. However, some media types will inevitably 648 have problems interoperating across different platforms. Problems 649 with different versions, byte ordering, and specifics of gateway 650 handling can and will arise. 652 Universal interoperability of media types is not required, but known 653 interoperability issues SHOULD be identified whenever possible. 654 Publication of a media type does not require an exhaustive review of 655 interoperability, and the interoperability considerations section is 656 subject to continuing evaluation. 658 These recommendations in this subsection apply regardless of the 659 registration tree involved. 661 4.6. Security Requirements 663 An analysis of security issues MUST be done for all types registered 664 in the standards tree. A similar analysis for media types registered 665 in the vendor or personal trees is encouraged but not required. 666 However, regardless of what security analysis has or has not been 667 done, all descriptions of security issues MUST be as accurate as 668 possible regardless of registration tree. In particular, a statement 669 that there are "no security issues associated with this type" MUST 670 NOT be confused with "the security issues associates with this type 671 have not been assessed". 673 There is absolutely no requirement that media types registered in any 674 tree be secure or completely free from risks. Nevertheless, all 675 known security risks MUST be identified in the registration of a 676 media type, again regardless of registration tree. 678 The security considerations section of all registrations is subject 679 to continuing evaluation and modification, and in particular MAY be 680 extended by use of the "comments on media types" mechanism described 681 in Section 5.4 below. 683 Some of the issues that need to be examined and described in a 684 security analysis of a media type are: 686 o Complex media types may include provisions for directives that 687 institute actions on a recipient's files or other resources. In 688 many cases provision is made for originators to specify arbitrary 689 actions in an unrestricted fashion that may then have devastating 690 effects. See the registration of the application/postscript media 691 type in [RFC2046] for an example of such directives and how they 692 can be described in a media type registration. 694 o Any security analysis MUST state whether or not they employ such 695 "active content", and if they do, they MUST state what steps have 696 been taken to protect users of the media type from harm. 698 o Complex media types may include provisions for directives that 699 institute actions that, while not directly harmful to the 700 recipient, may result in disclosure of information that either 701 facilitates a subsequent attack or else violates a recipient's 702 privacy in some way. Again, the registration of the application/ 703 postscript media type illustrates how such directives can be 704 handled. 706 o A media type that employs compression may provide an opportunity 707 for sending a small amount of data that, when received and 708 evaluated, expands enormously to consume all of the recipient's 709 resources. All media types SHOULD state whether or not they 710 employ compression, and if they do they SHOULD discuss what steps 711 need to be taken to avoid such attacks. 713 o A media type might be targeted for applications that require some 714 sort of security assurance but not provide the necessary security 715 mechanisms themselves. For example, a media type could be defined 716 for storage of sensitive medical information that in turn requires 717 external confidentiality and integrity protection services, or 718 which is designed for use only within a secure environment. Types 719 SHOULD always document whether or not they need such servies in 720 their security considerations. 722 4.7. Requirements specific to XML media types 724 There are a number of additional requirements specific to the 725 registration of XML media types. These requirements are specified in 726 [RFC3023]. 728 4.8. Encoding Requirements 730 Some transports impose restrictions on the type of data they can 731 carry. For example, Internet mail traditionally was limited to 7bit 732 US-ASCII text. Encoding schemes are often used to work around such 733 transport limitations. 735 It is therefore useful to note what sort of data a media type can 736 consist of as part of its registration. An "encoding considerations" 737 field is provided for this purpose. Possible values of this field 738 are: 740 7bit: The content of the media type consists solely of CRLF- 741 delimited 7bit US-ASCII text. 743 8bit: The content of the media type consists solely of CRLF- 744 delimited 8bit text. 746 binary: The content consists of an unrestricted sequence of octets. 748 framed: The content consists of a series of frames or packets 749 without internal framing or alignment indicators. Additional out- 750 of-band information is needed to interpret the data properly, 751 including but not necessarily limited to, knowledge of the 752 boundaries between successive frames and knowledge of the 753 transport mechanism. Note that media types of this sort cannot 754 simply be stored in a file or transported as a simple stream of 755 octets; therefore, such media types are unsuitable for use in many 756 traditional protocols. A commonly used transport with framed 757 encoding is the Real-time Transport Protocol, RTP. Additional 758 rules for framed encodings defined for transport using RTP are 759 given in [RFC4855]. 761 Additional restrictions on 7bit and 8bit text are given in Section 762 4.1.1 of [RFC2046]. 764 4.9. Usage and Implementation Non-requirements 766 In the asynchronous mail environment, where information on the 767 capabilities of the remote mail agent is frequently not available to 768 the sender, maximum interoperability is attained by restricting the 769 media types used to those "common" formats expected to be widely 770 implemented. This was asserted in the past as a reason to limit the 771 number of possible media types, and resulted in a registration 772 process with a significant hurdle and delay for those registering 773 media types. 775 However, the need for "common" media types does not require limiting 776 the registration of new media types. If a limited set of media types 777 is recommended for a particular application, that should be asserted 778 by a separate applicability statement specific for the application 779 and/or environment. 781 Therefore, universal support and implementation of a media type is 782 NOT a requirement for registration. However, if a media type is 783 explicitly intended for limited use, this MUST be noted in its 784 registration. The "Restrictions on Usage" field is provided for this 785 purpose. 787 4.10. Publication Requirements 789 Media types registered in the standards tree by the IETF itself MUST 790 be published as RFCs. RFC publication of vendor and personal media 791 type registrations is allowed but not required. In all cases the 792 IANA will retain copies of all media type registrations and "publish" 793 them as part of the media types registration tree itself. 795 As stated previously, standards tree registrations for media types 796 defined in documents produced by other standards bodies MUST be 797 described by a formal standards specification produced by that body. 798 Additionally, any copyright on the registration template MUST allow 799 the IANA to copy it into the IANA registry. 801 Other than IETF registrations in the standards tree, the registration 802 of a media type does not imply endorsement, approval, or 803 recommendation by the IANA or the IETF or even certification that the 804 specification is adequate. To become an Internet Standard, a 805 protocol or data object must go through the IETF standards process. 806 While it provides additional assurances when it is appropriate, this 807 is too difficult and too lengthy a process for the convenient 808 registration of media types. 810 The standards tree exists for media types that do require a 811 substantive review and approval process in a recognized standards 812 body. The vendor and personal trees exist for those media types that 813 do not require such a process. It is expected that applicability 814 statements for particular applications will be published from time to 815 time in the IETF, recommending implementation of, and support for, 816 media types that have proven particularly useful in those contexts. 818 As discussed above, registration of a top-level type requires 819 Standards Action in the IETF and, hence, the publication of a RFC on 820 the Standards Track. 822 4.11. Fragment Identifier Requirements 824 Media type registrations can specify how applications should 825 interpret fragment identifiers [RFC3986] associated with the media 826 type. 828 Media types are encouraged to adopt fragment identifier schemes that 829 are used with semantically similar media types. In particular, media 830 types that use a named structured syntax with a registered "+suffix" 831 MUST follow whatever fragment identifier rules are given in the 832 structured syntax suffix registration. 834 4.12. Additional Information 836 Various sorts of optional information SHOULD be included in the 837 specification of a media type if it is available: 839 o Magic number(s) (length, octet values). Magic numbers are byte 840 sequences that are always present at a given place in the file and 841 thus can be used to identify entities as being of a given media 842 type. 844 o File name extension(s) commonly used on one or more platforms to 845 indicate that some file contains a given media type. 847 o Mac OS File Type code(s) (4 octets) used to label files containing 848 a given media type. Some discussion of Macintosh file type codes 849 and their purpose can be found in [MacOSFileTypes]. 851 In the case of a registration in the standards tree, this additional 852 information MAY be provided in the formal specification of the media 853 type format. It is suggested that this be done by incorporating the 854 IANA media type registration form into the format specification 855 itself. 857 5. Media Type Registration Procedures 859 The media type registration procedure is not a formal standards 860 process, but rather an administrative procedure intended to allow 861 community comment and sanity checking without excessive time delay. 863 Normal IETF processes need to be followed for all IETF registrations 864 in the standards tree. The posting of an Internet Draft is a 865 necessary first step, followed by posting to the media-types@iana.org 866 list as discussed below. 868 5.1. Preliminary Community Review 870 Notice of a potential media type registration in the standards tree 871 SHOULD be sent to the media-types@iana.org mailing list for review. 872 This mailing list has been established for the purpose of reviewing 873 proposed media and access types. Registrations in other trees MAY be 874 sent to the list for review as well; doing so is entirely OPTIONAL, 875 but is strongly encouraged. 877 The intent of the public posting to this list is to solicit comments 878 and feedback on the choice of type/subtype name, the unambiguity of 879 the references with respect to versions and external profiling 880 information, and a review of any interoperability or security 881 considerations. The submitter may submit a revised registration 882 proposal or abandon the registration completely and at any time. 884 5.2. Submit request to IANA 886 Media types registered in the standards tree by the IETF itself MUST 887 be reviewed and approved by the IESG as part of the normal standards 888 process. Standards tree registrations by recognized standards bodies 889 as well as registrations in the vendor and personal tree are 890 submitted directly to the IANA, unless other arrangements were made 891 as part of a liaison agreement. In either case posting the 892 registration to the media-types@iana.org list for review prior to 893 submission is strongly encouraged. 895 Registration requests can be sent to iana@iana.org. A web form for 896 registration requests is also available: 898 http://www.iana.org/cgi-bin/mediatypes.pl 900 5.2.1. Provisional Registrations 902 Standardization processes often take considerable time to complete. 903 In order to facilitate prototyping and testing it is often helpful to 904 assign identifiers, including but not limited to media types, early 905 in the process. This way identifiers used during standards 906 development can remain unchanged once the process is complete and 907 implementations and documentation do not have to be updated. 909 Accordingly, a provisional registration process is provided to 910 support early assignment of media type names. A provisional 911 registration MAY be submitted to IANA for standards tree types. The 912 only required fields in such registrations are the media type name 913 and contact information (including the standards body name). 915 Upon receipt of a provisional registration, IANA will check the name 916 and contact information, then publish the registration in a separate 917 provisional registration list. 919 Provisional registrations MAY be updated or abandoned at any time. 921 5.3. Review and Approval 923 With the exception of provisional standards tree registrations, 924 registrations submitted to the IANA will be passed on to the media 925 types reviewer. The media types reviewer, who is appointed by the 926 IETF Applications Area Director(s), will review the registration to 927 make sure it meets the requirements set forth in this document. 928 Registrations that do not meet these requirements will be returned to 929 the submitter for revision. 931 Decisions made by the media types reviewer may be appealed to the 932 IESG using the procedure specified in section 6.5.4 of [RFC2026]. 934 Once a media type registration has passed review, the IANA will 935 register the media type and make the media type registration 936 available to the community. 938 In the case of standards tree registrations from other standards 939 bodies IANA will also check that the submitter is in fact a 940 recognized standards body. If the submitter is not currently 941 recognized as such the IESG will be asked to confirm their status. 942 Recognition from the IESG MUST be obtained before a standards tree 943 registration can proceed. 945 5.4. Comments on Media Type Registrations 947 Comments on registered media types may be submitted by members of the 948 community to the IANA at iana@iana.org. These comments will be 949 reviewed by the media types reviewer and then passed on to the 950 "owner" of the media type if possible. Submitters of comments may 951 request that their comment be attached to the media type registration 952 itself, and if the IANA approves of this, the comment will be made 953 accessible in conjunction with the type registration. 955 5.5. Location of Registered Media Type List 957 Media type registrations are listed by the IANA at: 959 http://www.iana.org/assignments/media-types/ 961 5.6. Change Procedures 963 Once a media type has been published by the IANA, the owner may 964 request a change to its definition. The descriptions of the 965 different registration trees above designate the "owners" of each 966 type of registration. The same procedure that would be appropriate 967 for the original registration request is used to process a change 968 request. 970 Media type registrations may not be deleted; media types that are no 971 longer believed appropriate for use can be declared OBSOLETE by a 972 change to their "intended use" field; such media types will be 973 clearly marked in the lists published by the IANA. 975 Significant changes to a media type's definition should be requested 976 only when there are serious omissions or errors in the published 977 specification. When review is required, a change request may be 978 denied if it renders entities that were valid under the previous 979 definition invalid under the new definition. 981 The owner of a media type may pass responsibility to another person 982 or agency by informing the IANA; this can be done without discussion 983 or review. 985 The IESG may reassign responsibility for a media type. The most 986 common case of this will be to enable changes to be made to types 987 where the author of the registration has died, moved out of contact 988 or is otherwise unable to make changes that are important to the 989 community. 991 5.7. Registration Template 993 Type name: 995 Subtype name: 997 Required parameters: 999 Optional parameters: 1001 Encoding considerations: 1003 Security considerations: 1005 Interoperability considerations: 1007 Published specification: 1009 Applications that use this media type: 1011 Fragment identifier considerations: 1013 Additional information: 1015 Deprecated alias names for this type: 1016 Magic number(s): 1017 File extension(s): 1018 Macintosh file type code(s): 1020 Person & email address to contact for further information: 1022 Intended usage: 1024 (One of COMMON, LIMITED USE or OBSOLETE.) 1026 Restrictions on usage: 1028 (Any restrictions on where the media type can be used go here.) 1030 Author: 1032 Change controller: 1034 Provisional registration? (standards tree only): 1036 (Any other information that the author deems interesting may be 1037 added below this line.) 1038 "N/A", written exactly that way, can be used in any field if desired 1039 to emphasize the fact that it does not apply or that the question was 1040 not omitted by accident. Do not use 'none' or other words that could 1041 be mistaken for a response. 1043 Limited use media types should also note in the applications list 1044 whether or not that list is exhaustive. 1046 6. Structured Syntax Suffix Registration Procedures 1048 Someone wishing to define a "+suffix" name for a structured syntax 1049 for use with a new media type registration SHOULD: 1051 1. Check IANA's registry of media type name suffixes to see whether 1052 or not there is already an entry for that well-defined structured 1053 syntax. 1055 2. If there is no entry for their suffix scheme, fill out the 1056 template (specified in Section 6.2) and include that with the 1057 media type registration. The template may be contained in an 1058 Internet Draft, alone or as part of some other protocol 1059 specification. The template may also be submitted in some other 1060 form (as part of another document or as a stand-alone document), 1061 but the contents will be treated as an "IETF Contribution" under 1062 the guidelines of BCP 78 [RFC5378]. 1064 3. Send a copy of the template or a pointer to the containing 1065 document (with specific reference to the section with the 1066 template) to the mailing list media-types@iana.org, requesting 1067 review. This may be combined with a request to review the media 1068 type registration. Allow a reasonable time for discussion and 1069 comments. 1071 4. Respond to review comments and make revisions to the proposed 1072 registration as needed to bring it into line with the guidelines 1073 given in this document. 1075 5. Submit the (possibly updated) registration template (or pointer 1076 to the document containing it) to IANA at iana@iana.org. 1078 Upon receipt of a structured syntax suffix registration request, 1080 1. IANA checks the submission for completeness; if sections are 1081 missing or citations are not correct, IANA rejects the 1082 registration request. 1084 2. IANA checks the current registry for an entry with the same name; 1085 if such a registry exists, IANA rejects the registration request. 1087 3. IANA requests Expert Review of the registration request against 1088 the corresponding guidelines. 1090 4. The Designated Expert may request additional review or 1091 discussion, as necessary. 1093 5. If Expert Review recommends registration, IANA adds the 1094 registration to the appropriate registry. 1096 6.1. Change Procedures 1098 Registrations may be updated in each registry by the same mechanism 1099 as required for an initial registration. In cases where the original 1100 definition of the scheme is contained in an IESG-approved document, 1101 update of the specification also requires IESG approval. 1103 6.2. Structured Syntax Suffix Registration Template 1105 This template describes the fields that must be supplied in a 1106 structured syntax suffix registration request: 1108 Name 1109 Full name of the well-defined structured syntax. 1111 +suffix 1112 Suffix used to indicate conformance to the syntax. 1114 References 1115 Include full citations for all specifications necessary to 1116 understand the structured syntax. 1118 Encoding considerations 1119 General guidance regarding encoding considerations for any type 1120 employing this syntax should be given here. The same requirements 1121 for media type encoding considerations given in Section 4.8 apply 1122 here. 1124 Interoperability considerations 1125 Any issues regarding the interoperable use of types employing this 1126 structured syntax should be given here. Examples would include 1127 the existence of incompatible versions of the syntax, issues 1128 combining certain charsets with the syntax, or incompatibilities 1129 with other types or protocols. 1131 Fragment identifier considerations 1132 Generic processing of fragment identifiers for any type employing 1133 this syntax should be described here. 1135 Security considerations 1136 Security considerations shared by media types employing this 1137 structured syntax must be specified here. The same requirements 1138 for media type security considerations given in Section 4.6 apply 1139 here, with the exception that option of not assessing the security 1140 considerations is not available for suffix registrations. 1142 Contact 1143 Person (including contact information) to contact for further 1144 information. 1146 Author/Change controller. 1147 Person (including contact information) authorized to change this 1148 suffix registration. 1150 7. Security Considerations 1152 Security requirements for media type registrations are discussed in 1153 Section 4.6. 1155 8. IANA Considerations 1157 The purpose of this document is to define IANA registries for media 1158 types and structured syntax suffixes as well as the procedures for 1159 managing these registries. Additionally, this document requires IANA 1160 to maintain a list of IESG-recognized standards bodies who are 1161 allowed to register types in the standards tree. 1163 This document also creates a new registry for structured syntax 1164 names: 1166 o The name is the "Structured Syntax Suffix" registry. 1168 o The registration process is specified in Section 6. 1170 o The information required for a registry entry as well as the entry 1171 format are specified in Section 6.2. 1173 o The initial content of the registry is specified in 1174 [I-D.appsawg-media-type-suffix-regs]. 1176 Finally, this document calls for the creation of a new email address, 1177 media-types@iana.org, for the media type review list, which replaces 1178 the ietf-types@iana.org address specified in RFC 4288. 1179 ietf-types@iana.org should be retained as an alias. 1181 9. Acknowledgements 1183 The current authors would like to acknowledge their debt to the late 1184 Dr. Jon Postel, whose general model of IANA registration procedures 1185 and specific contributions shaped the predecessors of this document 1186 [RFC2048] [RFC4288]. We hope that the current version is one with 1187 which he would have agreed but, as it is impossible to verify that 1188 agreement, we have regretfully removed his name as a co-author. 1190 Bjoern Hoehrmann, Barry Leiba, Murray Kucherawy, Alexey Melnikov, S. 1191 Moonesamy, Peter Saint-Andre, and Jeni Tennison provided many helpful 1192 review comments and suggestions. 1194 10. References 1196 10.1. Normative References 1198 [I-D.appsawg-media-type-suffix-regs] 1199 Hansen, T., "Additional Media Type Structured Syntax 1200 Suffixes", draft-appsawg-media-type-suffix-regs-00 (work 1201 in progress), April 2012. 1203 [I-D.ietf-appsawg-mime-default-charset] 1204 Melnikov, A. and J. Reschke, "Update to MIME regarding 1205 Charset Parameter Handling in Textual Media Types", 1206 draft-ietf-appsawg-mime-default-charset-01 (work in 1207 progress), March 2012. 1209 [RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail 1210 Extensions (MIME) Part One: Format of Internet Message 1211 Bodies", RFC 2045, November 1996. 1213 [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail 1214 Extensions (MIME) Part Two: Media Types", RFC 2046, 1215 November 1996. 1217 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1218 Requirement Levels", BCP 14, RFC 2119, March 1997. 1220 [RFC2978] Freed, N. and J. Postel, "IANA Charset Registration 1221 Procedures", BCP 19, RFC 2978, October 2000. 1223 [RFC3023] Murata, M., St. Laurent, S., and D. Kohn, "XML Media 1224 Types", RFC 3023, January 2001. 1226 [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 1227 10646", STD 63, RFC 3629, November 2003. 1229 [RFC3979] Bradner, S., "Intellectual Property Rights in IETF 1230 Technology", BCP 79, RFC 3979, March 2005. 1232 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 1233 Resource Identifier (URI): Generic Syntax", STD 66, 1234 RFC 3986, January 2005. 1236 [RFC4855] Casner, S., "Media Type Registration of RTP Payload 1237 Formats", RFC 4855, February 2007. 1239 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 1240 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 1241 May 2008. 1243 [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax 1244 Specifications: ABNF", STD 68, RFC 5234, January 2008. 1246 [RFC5378] Bradner, S. and J. Contreras, "Rights Contributors Provide 1247 to the IETF Trust", BCP 78, RFC 5378, November 2008. 1249 [RFC6532] Yang, A., Steel, S., and N. Freed, "Internationalized 1250 Email Headers", RFC 6532, January 2012. 1252 10.2. Informative References 1254 [I-D.ietf-appsawg-xdash] 1255 Saint-Andre, P. and D. Crocker, "Deprecating the X- Prefix 1256 and Similar Constructs in Application Protocols", 1257 draft-ietf-appsawg-xdash-05 (work in progress), 1258 April 2012. 1260 [MacOSFileTypes] 1261 Apple Computer, Inc., "Mac OS: File Type and Creator 1262 Codes, and File Formats", Apple Knowledge Base Article 1263 55381, June 1993, 1264 . 1266 [RFC2026] Bradner, S., "The Internet Standards Process -- Revision 1267 3", BCP 9, RFC 2026, October 1996. 1269 [RFC2048] Freed, N., Klensin, J., and J. Postel, "Multipurpose 1270 Internet Mail Extensions (MIME) Part Four: Registration 1271 Procedures", BCP 13, RFC 2048, November 1996. 1273 [RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded 1274 Word Extensions: 1275 Character Sets, Languages, and Continuations", RFC 2231, 1276 November 1997. 1278 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., 1279 Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext 1280 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. 1282 [RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and 1283 Registration Procedures", BCP 13, RFC 4288, December 2005. 1285 [RFC4844] Daigle, L. and Internet Architecture Board, "The RFC 1286 Series and RFC Editor", RFC 4844, July 2007. 1288 Appendix A. Grandfathered Media Types 1290 A number of media types with unfaceted subtype names, registered 1291 prior to 1996, would, if registered under the guidelines in this 1292 document, be given a faceted name and placed into either the vendor 1293 or personal trees. Reregistration of those types to reflect the 1294 appropriate trees is encouraged but not required. Ownership and 1295 change control principles outlined in this document apply to those 1296 types as if they had been registered in the trees described above. 1298 From time to time there may also be cases where a media type with an 1299 unfaceted subtype name has been widely deployed without being 1300 registered. (Note that this includes subtype names beginning with 1301 the "x-" prefix.) If possible such media type SHOULD be reregistered 1302 with a proper faceted subtype name. However, if this is not possible 1303 the type can, subject to approval by both the media types reviewer 1304 and the IESG, be registered in the proper tree with its unfaceted 1305 name. 1307 Appendix B. Changes Since RFC 4288 1309 o Suffixes to indicate the use of a particular structured syntax are 1310 now fully specified and a suffix registration process has been 1311 defined. 1313 o Registration of widely deployed unregistered unfaceted type names 1314 in the vendor or personal trees is now allowed, subject to 1315 approval by the media types reviewer and the IESG. 1317 o The standards tree registration process has been revised to 1318 include Expert Review and generalized to address cases like media 1319 types in non-IETF stream documents. 1321 o A field for fragment identifiers has been added to the 1322 registration template and brief directions for specifying fragment 1323 identifiers have been added. 1325 o The specification requirements for personal tree registrations 1326 have been changed to be the same as those for the vendor tree. 1327 The text has been changed to encourage (but not require) 1328 specification availability. 1330 o The definition of additional trees has been clarified to state 1331 that an IETF Standards Action is required. 1333 o Widely deployed types with "x-" names can now be registered as an 1334 exception in the vendor tree. 1336 o The requirements on changes to registrations have been loosened so 1337 minor changes are easier to make. 1339 o The registration process has been completely restructured so that 1340 with the exception of IETF-generated types in the standards tree, 1341 all requests are processed by IANA and not the IESG. 1343 o A provisional registration process has been added for early 1344 assignment of types in the standards tree. 1346 o Many editorial changes have been made throughout the document to 1347 make the requirements and processes it describes clearer and 1348 easier to follow. 1350 o The ability to specify a list of deprecated aliases for a media 1351 type has been added. 1353 o Types with names beginning with "x-" are no longer considered to 1354 be members of the unregistered "x." tree. As with any unfaceted 1355 type, special procedures have been added to allow registration of 1356 such types in an appropriate tree. 1358 o Changes to a type registered by a third party may now be made by 1359 the designated change controller even if that isn't the vendor or 1360 organization that created the type. However, the vendor or 1361 organization may elect to assert ownership and change controller 1362 over the type at any time. 1364 o Limited use media types are now asked to note whether or not the 1365 supplied list of applications employing the media type is 1366 exhaustive. 1368 o The ABNF for media type names has been further restricted to 1369 require that names begin with an alphanumeric character. 1371 o Mailing list review is no longer required prior to registration of 1372 media types. Additionally, the address associated with the media 1373 type review mailing list has been changed to media-types@iana.org. 1375 Authors' Addresses 1377 Ned Freed 1378 Oracle 1379 800 Royal Oaks 1380 Monrovia, CA 91016-6347 1381 USA 1383 Email: ned+ietf@mrochek.com 1385 John C. Klensin 1386 1770 Massachusetts Ave, #322 1387 Cambridge, MA 02140 1388 USA 1390 Email: john+ietf@jck.com 1392 Tony Hansen 1393 AT&T Laboratories 1394 200 Laurel Ave. 1395 Middletown, NJ 07748 1396 USA 1398 Email: tony+mtsuffix@maillennium.att.com