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'I-D.appsawg-media-type-suffix-regs' == Outdated reference: draft-ietf-appsawg-mime-default-charset has been published as RFC 6657 ** Obsolete normative reference: RFC 3023 (Obsoleted by RFC 7303) ** Obsolete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reference: RFC 3979 (Obsoleted by RFC 8179) ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126) == Outdated reference: draft-ietf-appsawg-xdash has been published as RFC 6648 -- Obsolete informational reference (is this intentional?): RFC 2048 (Obsoleted by RFC 4288,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 5987 (Obsoleted by RFC 8187) 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: December 6, 2012 T. Hansen 7 AT&T Laboratories 8 June 4, 2012 10 Media Type Specifications and Registration Procedures 11 draft-ietf-appsawg-media-type-regs-12 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 December 6, 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 . . . . . . . . . . . . 5 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 . . . . . . . . . . . . . . . . . . . 8 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 . . . . . . . . . . . . . . . . . . 16 79 4.7. Requirements specific to XML media types . . . . . . . . . 17 80 4.8. Encoding Requirements . . . . . . . . . . . . . . . . . . 17 81 4.9. Usage and Implementation Non-requirements . . . . . . . . 18 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 . . . . . . . . . . . . . . 20 86 5.1. Preliminary Community Review . . . . . . . . . . . . . . . 20 87 5.2. Submit request to IANA . . . . . . . . . . . . . . . . . . 20 88 5.2.1. Provisional Registrations . . . . . . . . . . . . . . 21 89 5.3. Review and Approval . . . . . . . . . . . . . . . . . . . 21 90 5.4. Comments on Media Type Registrations . . . . . . . . . . . 22 91 5.5. Change Procedures . . . . . . . . . . . . . . . . . . . . 22 92 5.6. Registration Template . . . . . . . . . . . . . . . . . . 23 93 6. Structured Syntax Suffix Registration Procedures . . . . . . . 24 94 6.1. Change Procedures . . . . . . . . . . . . . . . . . . . . 25 95 6.2. Structured Syntax Suffix Registration Template . . . . . . 25 97 7. Security Considerations . . . . . . . . . . . . . . . . . . . 26 98 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26 99 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 27 100 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 27 101 10.1. Normative References . . . . . . . . . . . . . . . . . . . 27 102 10.2. Informative References . . . . . . . . . . . . . . . . . . 29 103 Appendix A. Grandfathered Media Types . . . . . . . . . . . . . . 29 104 Appendix B. Changes Since RFC 4288 . . . . . . . . . . . . . . . 30 105 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. 114 The mechanism used to label such content is a media type, consisting 115 of a top-level type and a subtype, which is further structured into 116 trees. Optionally, media types can define companion data, known as 117 parameters. 119 A registration process is needed for these labels, so that that the 120 set of such values are defined in a reasonably orderly, well- 121 specified, and public manner. 123 This document specifies the criteria for media type registrations and 124 defines the procedures to be used to register media types (Section 5) 125 as well as media type structured suffixes (Section 6) in the Internet 126 Assigned Numbers Authority (IANA) central registry. 128 The location of the media type registry managed by these procedures 129 is: 131 http://www.iana.org/assignments/media-types/ 133 1.1. Historical Note 135 The media type registration process was initially defined for 136 registering media types for use in the context of the asynchronous 137 Internet mail environment. In this mail environment there is a need 138 to limit the number of possible media types, to increase the 139 likelihood of interoperability when the capabilities of the remote 140 mail system are not known. As media types are used in new 141 environments in which the proliferation of media types is not a 142 hindrance to interoperability, the original procedure proved 143 excessively restrictive and had to be generalized. This was 144 initially done in [RFC2048], but the procedure defined there was 145 still part of the MIME document set. The media type specification 146 and registration procedure has now been moved to this separate 147 document, to make it clear that it is independent of MIME. 149 It may be desirable to restrict the use of media types to specific 150 environments or to prohibit their use in other environments. This 151 revision incorporates such restrictions into media type registrations 152 in a systematic way. See Section 4.9 for additional discussion. 154 1.2. Conventions Used in This Document 156 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 157 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 158 document are to be interpreted as described in [RFC2119] when they 159 appear in ALL CAPS. They may also appear in lower or mixed case as 160 plain English words, without any normative meaning. 162 This specification makes use of the Augmented Backus-Naur Form (ABNF) 163 [RFC5234] notation, including the core rules defined in Appendix A of 164 that document. 166 2. Media Type Registration Preliminaries 168 Registration of a new media type or types starts with the 169 construction of a registration proposal. Registration may occur 170 within several different registration trees that have different 171 requirements, as discussed below. In general, a new registration 172 proposal is circulated and reviewed in a fashion appropriate to the 173 tree involved. The media type is then registered if the proposal is 174 acceptable. The following sections describe the requirements and 175 procedures used for each of the different registration trees. 177 3. Registration Trees and Subtype Names 179 In order to increase the efficiency and flexibility of the 180 registration process, different structures of subtype names can be 181 registered to accommodate the different natural requirements for, 182 e.g., a subtype that will be recommended for wide support and 183 implementation by the Internet community, or a subtype that is used 184 to move files associated with proprietary software. The following 185 subsections define registration "trees" that are distinguished by the 186 use of faceted names, e.g., names of the form 187 "tree.subtree...subtype". Note that some media types defined prior 188 to this document do not conform to the naming conventions described 189 below. See Appendix A for a discussion of them. 191 3.1. Standards Tree 193 The standards tree is intended for types of general interest to the 194 Internet community. Registrations in the standards tree MUST be 195 either: 197 1. in the case of registrations in IETF specifications, approved 198 directly by the IESG, or 200 2. registered by a recognized standards body using the 201 "Specification Required" IANA registration policy [RFC5226] 202 (which implies Expert Review). 204 The first procedure is used for registering registrations from IETF 205 Consensus documents, or in rare cases when registering a 206 grandfathered (see Appendix A) and/or otherwise incomplete 207 registration is in the interest of the Internet community. The 208 registration proposal MUST be published as an RFC. When the RFC is 209 in the IETF stream it is an IETF Consensus RFC, which can be on the 210 Standards Track, a BCP, Informational, or Experimental. 211 Registrations published in non-IETF RFC streams are also allowed, and 212 require IESG approval. A registration can be either in a standalone 213 "registration only" RFC or incorporated into a more general 214 specification of some sort. 216 In the second case the IESG makes a one time decision on whether the 217 registration submitter represents a recognized standards body; after 218 that, a Media Types Reviewer (Designated Expert or a group of 219 Designated Experts) performs the Expert Review as specified in this 220 document. Subsequent submissions from the same source do not involve 221 the IESG. The format MUST be described by a formal standards 222 specification produced by the submitting standards body. 224 Media types in the standards tree MUST NOT have faceted names, unless 225 they are grandfathered in using the process described in Appendix A. 227 The "owner" of a media type registered in the standards tree is 228 assumed to be the standards body itself. Modification or alteration 229 of the specification uses the same level of processing (e.g., a 230 registration submitted on Standards Track can be revised in another 231 Standards Track RFC, but cannot be revised in an Informational RFC) 232 required for the initial registration. 234 Standards-tree registrations from recognized standards bodies may be 235 submitted directly to the IANA, where they will undergo Expert Review 236 [RFC5226] prior to approval. In this case, the Expert Reviewer(s) 237 will, among other things, ensure that the required specification 238 provides adequate documentation. 240 3.2. Vendor Tree 242 The vendor tree is used for media types associated with publicly 243 available products. "Vendor" and "producer" are construed very 244 broadly in this context and are considered equivalent. Note that 245 industry consortia as well as non-commercial entities that do not 246 qualify as recognized standards bodies can quite appropriately 247 register media types in the vendor tree. 249 A registration may be placed in the vendor tree by anyone who needs 250 to interchange files associated with some product or set of products. 251 However, the registration properly belongs to the vendor or 252 organization producing the software that employs the type being 253 registered, and that vendor or organization can at any time elect to 254 assert ownership of a registration done by a third party in order to 255 correct or update it. See Section 5.5 for additional information. 257 When a third party registers a type on behalf of someone else both 258 entities SHOULD be noted in the Change Controller field in the 259 registration. One possible format for this would be "Foo, on behalf 260 of Bar". 262 Registrations in the vendor tree will be distinguished by the leading 263 facet "vnd.". That may be followed, at the discretion of the 264 registrant, by either a media subtype name from a well-known producer 265 (e.g., "vnd.mudpie") or by an IANA-approved designation of the 266 producer's name that is followed by a media type or product 267 designation (e.g., vnd.bigcompany.funnypictures). 269 While public exposure and review of media types to be registered in 270 the vendor tree is not required, using the media-types@iana.org 271 mailing list for review is encouraged to improve the quality of those 272 specifications. Registrations in the vendor tree may be submitted 273 directly to the IANA, where they will undergo Expert Review [RFC5226] 274 prior to approval. 276 3.3. Personal or Vanity Tree 278 Registrations for media types created experimentally or as part of 279 products that are not distributed commercially may be registered in 280 the personal or vanity tree. The registrations are distinguished by 281 the leading facet "prs.". 283 The owner of "personal" registrations and associated specifications 284 is the person or entity making the registration, or one to whom 285 responsibility has been transferred as described below. 287 While public exposure and review of media types to be registered in 288 the personal tree is not required, using the media-types@iana.org 289 mailing list (see Section 5.1) for review is encouraged to improve 290 the quality of those specifications. Registrations in the personal 291 tree may be submitted directly to the IANA, where they will undergo 292 Expert Review [RFC5226] prior to approval. 294 3.4. Unregistered x. Tree 296 Subtype names with "x." as the first facet may be used for types 297 intended exclusively for use in private, local environments. Types 298 in this tree cannot be registered and are intended for use only with 299 the active agreement of the parties exchanging them. 301 However, with the simplified registration procedures described above 302 for vendor and personal trees, it should rarely, if ever, be 303 necessary to use unregistered types. Therefore, use of types in the 304 "x." tree is strongly discouraged. 306 Note that types with names beginning with "x-" are no longer 307 considered to members of this tree (see [I-D.ietf-appsawg-xdash]). 308 Also note that if a generally useful and widely deployed type 309 incorrectly ends up with an "x-" name prefix, it MAY be registered 310 using its current name in an alternate tree by following the 311 procedure defined in Appendix A. 313 3.5. Additional Registration Trees 315 From time to time and as required by the community, new top-level 316 registration trees may be created by IETF Standards Action. It is 317 explicitly assumed that these trees may be created for external 318 registration and management by well-known permanent bodies; for 319 example, scientific societies may register media types specific to 320 the sciences they cover. In general, the quality of review of 321 specifications for one of these additional registration trees is 322 expected to be equivalent to registrations in the standards tree by a 323 recognized Standards Development Organization. When the IETF 324 performs such review, it needs to consider the greater expertise of 325 the requesting body with respect to the subject media type. 327 4. Registration Requirements 329 Media type registrations are all expected to conform to various 330 requirements laid out in the following sections. Note that 331 requirement specifics sometimes vary depending on the registration 332 tree, again as detailed in the following sections. 334 4.1. Functionality Requirement 336 Media types MUST function as actual media formats. Registration of 337 things that are better thought of as a transfer encoding, as a 338 charset, or as a collection of separate entities of another type, is 339 not allowed. For example, although applications exist to decode the 340 base64 transfer encoding [RFC2045], base64 cannot be registered as a 341 media type. 343 This requirement applies regardless of the registration tree 344 involved. 346 4.2. Naming Requirements 348 All registered media types MUST be assigned top-level type and 349 subtype names. The combination of these names serves to uniquely 350 identify the media type, and the subtype name facet (or the absence 351 of one) identifies the registration tree. Both top-level type and 352 subtype names are case-insensitive. 354 Type and subtype names MUST conform to the following ABNF: 356 type-name = restricted-name 357 subtype-name = restricted-name 359 restricted-name = restricted-name-first *126restricted-name-chars 360 restricted-name-first = ALPHA / DIGIT 361 restricted-name-chars = ALPHA / DIGIT / "!" / "#" / 362 "$" / "&" / "-" / "^" / "_" 363 restricted-name-chars =/ "." ; Characters before first dot always 364 ; specify a facet name 365 restricted-name-chars =/ "+" ; Characters after last plus always 366 ; specify a structured syntax suffix 368 Note that this syntax is somewhat more restrictive than what is 369 allowed by the ABNF in section 5.1 of [RFC2045] or section 4.2 of 370 [RFC4288]. Also note that while this syntax allows names of up to 371 127 characters, implementation limits may make such long names 372 problematic. For this reason the components of names SHOULD be 373 limited to 64 characters. 375 Although the name syntax treats "." as equivalent to any other 376 character, characters before any initial "." always specify the 377 registration facet. Note that this means that facet-less standards 378 tree registrations cannot use periods in the subtype name. 380 Similarly, "+" is used in subtype names to introduce a structured 381 syntax specifier suffix. Structured syntax suffix requirements are 382 specified in Section 4.2.8. 384 While it is possible for a given media type to be assigned additional 385 names, the use of different names to identify the same media type is 386 discouraged. 388 These requirements apply regardless of the registration tree 389 involved. 391 The choice of top-level type MUST take into account the nature of 392 media type involved. New subtypes of top-level types MUST conform to 393 the restrictions of the top-level type, if any. The following 394 sections describe each of the initial set of top-level types and 395 their associated restrictions. Additionally, various protocols, 396 including but not limited to HTTP and MIME, MAY impose additional 397 restrictions on the media types they can transport. (See [RFC2046] 398 for additional information on the restrictions MIME imposes.) 400 4.2.1. Text Media Types 402 The "text" top-level type is intended for sending material that is 403 principally textual in form. 405 Many subtypes of text, notably including the subtype "text/plain", 406 which is a generic subtype for plain text defined in [RFC2046], 407 define a "charset" parameter. If a "charset" parameter is defined 408 for a particular subtype of text, it MUST be used to specify a 409 charset name defined in accordance to the procedures laid out in 410 [RFC2978]. 412 As specified in [I-D.ietf-appsawg-mime-default-charset], a "charset" 413 parameter SHOULD NOT be specified when charset information is 414 transported inside the payload (e.g., as in "text/xml"). 416 If a "charset" parameter is specified, it SHOULD be a required 417 parameter, eliminating the options of specifying a default value. If 418 there is a strong reason for the parameter to be optional despite 419 this advice, each subtype MAY specify its own default value, or 420 alternately, it MAY specify that there is no default value. Finally, 421 the "UTF-8" charset [RFC3629] SHOULD be selected as the default. See 422 [I-D.ietf-appsawg-mime-default-charset] for additional information on 423 the use of "charset" parameters in conjunction with subtypes of text. 425 Regardless of what approach is chosen, all text/* registrations MUST 426 clearly specify how the charset is determined; relying on the US- 427 ASCII default defined in Section 4.1.2 of [RFC2046] is no longer 428 permitted. If explanatory text is needed this SHOULD be placed in 429 the additional information section of the registration. 431 Plain text does not provide for or allow formatting commands, font 432 attribute specifications, processing instructions, interpretation 433 directives, or content markup. Plain text is seen simply as a linear 434 sequence of characters, possibly interrupted by line breaks or page 435 breaks. Plain text MAY allow the stacking of several characters in 436 the same position in the text. Plain text in scripts like Arabic and 437 Hebrew may also include facilities that allow the arbitrary mixing of 438 text segments with different writing directions. 440 Beyond plain text, there are many formats for representing what might 441 be known as "rich text". An interesting characteristic of many such 442 representations is that they are to some extent readable even without 443 the software that interprets them. It is useful to distinguish them, 444 at the highest level, from such unreadable data as images, audio, or 445 text represented in an unreadable form. In the absence of 446 appropriate interpretation software, it is reasonable to present 447 subtypes of "text" to the user, while it is not reasonable to do so 448 with most non-textual data. Such formatted textual data can be 449 represented using subtypes of "text". 451 4.2.2. Image Media Types 453 A top-level type of "image" indicates that the content specifies one 454 or more individual images. The subtype names the specific image 455 format. 457 4.2.3. Audio Media Types 459 A top-level type of "audio" indicates that the content contains audio 460 data. The subtype names the specific audio format. 462 4.2.4. Video Media Types 464 A top-level type of "video" indicates that the content specifies a 465 time-varying-picture image, possibly with color and coordinated 466 sound. The term 'video' is used in its most generic sense, rather 467 than with reference to any particular technology or format, and is 468 not meant to preclude subtypes such as animated drawings encoded 469 compactly. 471 Note that although in general the mixing of multiple kinds media in a 472 single body is discouraged [RFC2046], it is recognized that many 473 video formats include a representation for synchronized audio and/or 474 text, and this is explicitly permitted for subtypes of "video". 476 4.2.5. Application Media Types 478 The "application" top-level type is to be used for discrete data that 479 do not fit under any of the other type names, and particularly for 480 data to be processed by some type of application program. This is 481 information that must be processed by an application before it is 482 viewable or usable by a user. Expected uses for the "application" 483 type name include but are not limited to file transfer, spreadsheets, 484 presentations, scheduling data, and languages for "active" 485 (computational) material. (The last, in particular, can pose 486 security problems that must be understood by implementors. The 487 "application/postscript" media type registration in [RFC2046] 488 provides a good example of how to handle these issues.) 490 For example, a meeting scheduler might define a standard 491 representation for information about proposed meeting dates. An 492 intelligent user agent would use this information to conduct a dialog 493 with the user, and might then send additional material based on that 494 dialog. More generally, there have been several "active" languages 495 developed in which programs in a suitably specialized language are 496 transported to a remote location and automatically run in the 497 recipient's environment. Such applications may be defined as 498 subtypes of the "application" top-level type. 500 The subtype of "application" will often either be the name or include 501 part of the name of the application for which the data are intended. 502 This does not mean, however, that any application program name may 503 simply be used freely as a subtype of "application"; the subtype 504 needs to be registered. 506 4.2.6. Multipart and Message Media Types 508 Multipart and message are composite types, that is, they provide a 509 means of encapsulating zero or more objects, each one a separate 510 media type. 512 All subtypes of multipart and message MUST conform to the syntax 513 rules and other requirements specified in [RFC2046] and amended by 514 Section 3.5 of [RFC6532]. 516 4.2.7. Additional Top-level Types 518 In some cases a new media type may not "fit" under any currently 519 defined top-level type names. Such cases are expected to be quite 520 rare. However, if such a case does arise a new type name can be 521 defined to accommodate it. Such a definition MUST be done via 522 standards-track RFC; no other mechanism can be used to define 523 additional type name. 525 4.2.8. Structured Syntax Name Suffixes 527 XML in MIME [RFC3023] defined the first such augmentation to the 528 media type definition to additionally specify the underlying 529 structure of that media type. To quote: 531 This document also standardizes a convention (using the suffix 532 '+xml') for naming media types ... when those media types 533 represent XML MIME (Multipurpose Internet Mail Extensions) 534 entities. 536 That is, it specified a suffix (in that case, "+xml") to be appended 537 to the base subtype name. 539 Since this was published, the de facto practice has arisen for using 540 this suffix convention for other well-known structuring syntaxes. In 541 particular, media types have been registered with suffixes such as 542 "+der", "+fastinfoset" and "+json". This specification formalizes 543 this practice and sets up a registry for structured type name 544 suffixes. 546 The primary guideline for whether a structured type name suffix is 547 registrable is that it be described by a readily-available 548 description, preferably within a document published by an established 549 standards organization, and for which there's a reference that can be 550 used in a Normative References section of an RFC. 552 Media types that make use of a named structured syntax SHOULD use the 553 appropriate registered "+suffix" for that structured syntax when they 554 are registered. By the same token, media types MUST NOT be given 555 names incorporating suffixes for structured syntaxes they do not 556 actually employ. "+suffix" constructs for as-yet unregistered 557 structured syntaxes SHOULD NOT be used, given the possibility of 558 conflicts with future suffix definitions. 560 4.2.9. Deprecated Aliases 562 In some cases a single media type may have been widely deployed prior 563 to registration under multiple names. In such cases a preferred name 564 MUST be chosen for the media type and applications MUST use this to 565 be compliant with the type's registration. However, a list of 566 deprecated aliases the type is known by MAY be supplied as additional 567 information in order to assist applications in processing the media 568 type properly. 570 4.3. Parameter Requirements 572 Media types MAY elect to use one or more media type parameters, or 573 some parameters may be automatically made available to the media type 574 by virtue of being a subtype of a content type that defines a set of 575 parameters applicable to any of its subtypes. In either case, the 576 names, values, and meanings of any parameters MUST be fully specified 577 when a media type is registered in the standards tree, and SHOULD be 578 specified as completely as possible when media types are registered 579 in the vendor or personal trees. 581 Parameter names have the syntax as media type names and values: 583 parameter-name = restricted-name 585 Note that this syntax is somewhat more restrictive than what is 586 allowed by the ABNF in [RFC2045] and amended by [RFC2231]. 588 Parameter names are case-insensitive and no meaning is attached to 589 the order in which they appear. It is an error for a specific 590 parameter to be specified more than once. 592 There is no defined syntax for parameter values. Therefore 593 registrations MUST specify parameter value syntax. Additionally, 594 some transports impose restrictions on parameter value syntax, so 595 care needs be taken to limit the use of potentially problematic 596 syntaxes; e.g., pure binary valued parameters, while permitted in 597 some protocols, are best avoided. 599 Note that a protocol can impose further restrictions on parameter 600 value syntax, depending on how it chooses to represent parameters. 601 Both MIME [RFC2045] [RFC2231] and HTTP [RFC2045] [RFC5987] allow 602 binary parameters as well as parameter values expressed in a specific 603 charset, but other protocols may be less flexible. 605 New parameters SHOULD NOT be defined as a way to introduce new 606 functionality in types registered in the standards tree, although new 607 parameters MAY be added to convey additional information that does 608 not otherwise change existing functionality. An example of this 609 would be a "revision" parameter to indicate a revision level of an 610 external specification such as JPEG. Similar behavior is encouraged 611 for media types registered in the vendor or personal trees, but is 612 not required. 614 Changes to parameters (including the introduction of new ones) is 615 managed in the same manner as other changes to the media type; see 616 Section 5.5. 618 4.4. Canonicalization and Format Requirements 620 All registered media types MUST employ a single, canonical data 621 format, regardless of registration tree. 623 A permanent and readily available public specification of the format 624 for the media type MUST exist for all types registered in the 625 standards tree, and this specification MUST provide sufficient detail 626 so that interoperability between independent implementations using 627 the media type is possible. This specification MUST at a minimum be 628 referenced by, if it is not actually included in, the media type 629 registration proposal itself. 631 The specifications of format and processing particulars may or may 632 not be publicly available for media types registered in the vendor 633 and personal trees, and such registrations are explicitly permitted 634 to limit the information in the registration to which software and 635 version produce or process such media types. As such, references to 636 or inclusion of format specifications in registrations is encouraged 637 but not required. Note, however, that the public availability of a 638 meaningful specification will often make the difference between 639 simply having a name reserved so that there are no conflicts with 640 other uses and having the potential for other implementations of the 641 media type and useful interoperation with them. 643 Some media types involve the use of patented technology. The 644 registration of media types involving patented technology is 645 specifically permitted. However, the restrictions set forth in BCP 646 79 [RFC3979] and BCP 78 [RFC5378] on the use of patented technology 647 in IETF standards-track protocols must be respected when the 648 specification of a media type is part of a standards-track protocol. 649 In addition, other standards bodies making use of the standards tree 650 may have their own rules regarding intellectual property that must be 651 observed in their registrations. 653 IPR disclosures for registrations in the vendor and personal tree are 654 encouraged but not required. 656 4.5. Interchange Recommendations 658 Media types SHOULD interoperate across as many systems and 659 applications as possible. However, some media types will inevitably 660 have problems interoperating across different platforms. Problems 661 with different versions, byte ordering, and specifics of gateway 662 handling can and will arise. 664 Universal interoperability of media types is not required, but known 665 interoperability issues SHOULD be identified whenever possible. 666 Publication of a media type does not require an exhaustive review of 667 interoperability, and the interoperability considerations section is 668 subject to continuing evaluation. 670 These recommendations in this subsection apply regardless of the 671 registration tree involved. 673 4.6. Security Requirements 675 An analysis of security issues MUST be done for all types registered 676 in the standards tree. A similar analysis for media types registered 677 in the vendor or personal trees is encouraged but not required. 678 However, regardless of what security analysis has or has not been 679 done, all descriptions of security issues MUST be as accurate as 680 possible regardless of registration tree. In particular, a statement 681 that there are "no security issues associated with this type" MUST 682 NOT be confused with "the security issues associates with this type 683 have not been assessed". 685 There is absolutely no requirement that media types registered in any 686 tree be secure or completely free from risks. Nevertheless, all 687 known security risks MUST be identified in the registration of a 688 media type, again regardless of registration tree. 690 The security considerations section of all registrations is subject 691 to continuing evaluation and modification, and in particular MAY be 692 extended by use of the "comments on media types" mechanism described 693 in Section 5.4 below. 695 Some of the issues that need to be examined and described in a 696 security analysis of a media type are: 698 o Complex media types may include provisions for directives that 699 institute actions on a recipient's files or other resources. In 700 many cases provision is made for originators to specify arbitrary 701 actions in an unrestricted fashion that may then have devastating 702 effects. See the registration of the application/postscript media 703 type in [RFC2046] for an example of such directives and how they 704 can be described in a media type registration. 706 o Any security analysis MUST state whether or not they employ such 707 "active content", and if they do, they MUST state what steps have 708 been taken, or MUST be taken by applications of the media type, to 709 protect users of the media type from harm. 711 o Complex media types may include provisions for directives that 712 institute actions that, while not directly harmful to the 713 recipient, may result in disclosure of information that either 714 facilitates a subsequent attack or else violates a recipient's 715 privacy in some way. Again, the registration of the application/ 716 postscript media type illustrates how such directives can be 717 handled. 719 o A media type that employs compression may provide an opportunity 720 for sending a small amount of data that, when received and 721 evaluated, expands enormously to consume all of the recipient's 722 resources. All media types SHOULD state whether or not they 723 employ compression, and if they do they SHOULD discuss what steps 724 need to be taken to avoid such attacks. 726 o A media type might be targeted for applications that require some 727 sort of security assurance but not provide the necessary security 728 mechanisms themselves. For example, a media type could be defined 729 for storage of sensitive medical information that in turn requires 730 external confidentiality and integrity protection services, or 731 which is designed for use only within a secure environment. Types 732 SHOULD always document whether or not they need such services in 733 their security considerations. 735 4.7. Requirements specific to XML media types 737 There are a number of additional requirements specific to the 738 registration of XML media types. These requirements are specified in 739 [RFC3023]. 741 4.8. Encoding Requirements 743 Some transports impose restrictions on the type of data they can 744 carry. For example, Internet mail traditionally was limited to 7bit 745 US-ASCII text. Encoding schemes are often used to work around such 746 transport limitations. 748 It is therefore useful to note what sort of data a media type can 749 consist of as part of its registration. An "encoding considerations" 750 field is provided for this purpose. Possible values of this field 751 are: 753 7bit: The content of the media type consists solely of CRLF- 754 delimited 7bit US-ASCII text. 756 8bit: The content of the media type consists solely of CRLF- 757 delimited 8bit text. 759 binary: The content consists of an unrestricted sequence of octets. 761 framed: The content consists of a series of frames or packets 762 without internal framing or alignment indicators. Additional out- 763 of-band information is needed to interpret the data properly, 764 including but not necessarily limited to, knowledge of the 765 boundaries between successive frames and knowledge of the 766 transport mechanism. Note that media types of this sort cannot 767 simply be stored in a file or transported as a simple stream of 768 octets; therefore, such media types are unsuitable for use in many 769 traditional protocols. A commonly used transport with framed 770 encoding is the Real-time Transport Protocol, RTP. Additional 771 rules for framed encodings defined for transport using RTP are 772 given in [RFC4855]. 774 Additional restrictions on 7bit and 8bit text are given in Section 775 4.1.1 of [RFC2046]. 777 4.9. Usage and Implementation Non-requirements 779 In the asynchronous mail environment, where information on the 780 capabilities of the remote mail agent is frequently not available to 781 the sender, maximum interoperability is attained by restricting the 782 media types used to those "common" formats expected to be widely 783 implemented. This was asserted in the past as a reason to limit the 784 number of possible media types, and resulted in a registration 785 process with a significant hurdle and delay for those registering 786 media types. 788 However, the need for "common" media types does not require limiting 789 the registration of new media types. If a limited set of media types 790 is recommended for a particular application, that should be asserted 791 by a separate applicability statement specific for the application 792 and/or environment. 794 Therefore, universal support and implementation of a media type is 795 NOT a requirement for registration. However, if a media type is 796 explicitly intended for limited use, this MUST be noted in its 797 registration. The "Restrictions on Usage" field is provided for this 798 purpose. 800 4.10. Publication Requirements 802 Media types registered in the standards tree by the IETF itself MUST 803 be published as RFCs. RFC publication of vendor and personal media 804 type registrations is allowed but not required. In all cases the 805 IANA will retain copies of all media type registrations and "publish" 806 them as part of the media types registration tree itself. 808 As stated previously, standards tree registrations for media types 809 defined in documents produced by other standards bodies MUST be 810 described by a formal standards specification produced by that body. 811 Additionally, any copyright on the registration template MUST allow 812 the IANA to copy it into the IANA registry. 814 Other than IETF registrations in the standards tree, the registration 815 of a media type does not imply endorsement, approval, or 816 recommendation by the IANA or the IETF or even certification that the 817 specification is adequate. To become an Internet Standard, a 818 protocol or data object must go through the IETF standards process. 819 While it provides additional assurances when it is appropriate, this 820 is too difficult and too lengthy a process for the convenient 821 registration of media types. 823 The standards tree exists for media types that do require a 824 substantive review and approval process in a recognized standards 825 body. The vendor and personal trees exist for those media types that 826 do not require such a process. It is expected that applicability 827 statements for particular applications will be published from time to 828 time in the IETF, recommending implementation of, and support for, 829 media types that have proven particularly useful in those contexts. 831 As discussed above, registration of a top-level type requires 832 Standards Action in the IETF and, hence, the publication of a RFC on 833 the Standards Track. 835 4.11. Fragment Identifier Requirements 837 Media type registrations can specify how applications should 838 interpret fragment identifiers (specified in section 3.5 of 839 [RFC3986]) associated with the media type. 841 Media types are encouraged to adopt fragment identifier schemes that 842 are used with semantically similar media types. In particular, media 843 types that use a named structured syntax with a registered "+suffix" 844 MUST follow whatever fragment identifier rules are given in the 845 structured syntax suffix registration. 847 4.12. Additional Information 849 Various sorts of optional information SHOULD be included in the 850 specification of a media type if it is available: 852 o Magic number(s) (length, octet values). Magic numbers are byte 853 sequences that are always present at a given place in the file and 854 thus can be used to identify entities as being of a given media 855 type. 857 o File name extension(s) commonly used on one or more platforms to 858 indicate that some file contains a given media type. 860 o Mac OS File Type code(s) (4 octets) used to label files containing 861 a given media type. Some discussion of Macintosh file type codes 862 and their purpose can be found in [MacOSFileTypes]. 864 In the case of a registration in the standards tree, this additional 865 information MAY be provided in the formal specification of the media 866 type format. It is suggested that this be done by incorporating the 867 IANA media type registration form into the format specification 868 itself. 870 5. Media Type Registration Procedures 872 The media type registration procedure is not a formal standards 873 process, but rather an administrative procedure intended to allow 874 community comment and sanity checking without excessive time delay. 876 Normal IETF processes need to be followed for all IETF registrations 877 in the standards tree. The posting of an Internet Draft is a 878 necessary first step, followed by posting to the media-types@iana.org 879 list as discussed below. 881 5.1. Preliminary Community Review 883 Notice of a potential media type registration in the standards tree 884 SHOULD be sent to the media-types@iana.org mailing list for review. 885 This mailing list has been established for the purpose of reviewing 886 proposed media and access types. Registrations in other trees MAY be 887 sent to the list for review as well; doing so is entirely OPTIONAL, 888 but is strongly encouraged. 890 The intent of the public posting to this list is to solicit comments 891 and feedback on the choice of type/subtype name, the unambiguity of 892 the references with respect to versions and external profiling 893 information, and a review of any interoperability or security 894 considerations. The submitter may submit a revised registration 895 proposal or abandon the registration completely and at any time. 897 5.2. Submit request to IANA 899 Media types registered in the standards tree by the IETF itself MUST 900 be reviewed and approved by the IESG as part of the normal standards 901 process. Standards tree registrations by recognized standards bodies 902 as well as registrations in the vendor and personal tree are 903 submitted directly to the IANA, unless other arrangements were made 904 as part of a liaison agreement. In either case posting the 905 registration to the media-types@iana.org list for review prior to 906 submission is strongly encouraged. 908 Registration requests can be sent to iana@iana.org. A web form for 909 registration requests is also available: 911 http://www.iana.org/cgi-bin/mediatypes.pl 913 5.2.1. Provisional Registrations 915 Standardization processes often take considerable time to complete. 916 In order to facilitate prototyping and testing it is often helpful to 917 assign identifiers, including but not limited to media types, early 918 in the process. This way identifiers used during standards 919 development can remain unchanged once the process is complete and 920 implementations and documentation do not have to be updated. 922 Accordingly, a provisional registration process is provided to 923 support early assignment of media type names in the standards tree. 924 A provisional registration MAY be submitted to IANA for standards 925 tree types. The only required fields in such registrations are the 926 media type name and contact information (including the standards body 927 name). 929 Upon receipt of a provisional registration, IANA will check the name 930 and contact information, then publish the registration in a separate 931 publicly visible provisional registration list. 933 Provisional registrations MAY be updated or abandoned at any time. 934 When the registration is abandoned the media type is no longer 935 registered in any sense; it can subsequently be registered just like 936 any other unassigned media type name. 938 5.3. Review and Approval 940 With the exception of provisional standards tree registrations, 941 registrations submitted to the IANA will be passed on to the media 942 types reviewer. The media types reviewer, who is appointed by the 943 IETF Applications Area Director(s), will review the registration to 944 make sure it meets the requirements set forth in this document. 945 Registrations that do not meet these requirements will be returned to 946 the submitter for revision. 948 Decisions made by the media types reviewer may be appealed to the 949 IESG using the procedure specified in section 6.5.4 of [RFC2026]. 951 Once a media type registration has passed review, the IANA will 952 register the media type and make the media type registration 953 available to the community. 955 In the case of standards tree registrations from other standards 956 bodies IANA will also check that the submitter is in fact a 957 recognized standards body. If the submitter is not currently 958 recognized as such the IESG will be asked to confirm their status. 959 Recognition from the IESG MUST be obtained before a standards tree 960 registration can proceed. 962 5.4. Comments on Media Type Registrations 964 Comments on registered media types may be submitted by members of the 965 community to the IANA at iana@iana.org. These comments will be 966 reviewed by the media types reviewer and then passed on to the 967 "owner" of the media type if possible. Submitters of comments may 968 request that their comment be attached to the media type registration 969 itself, and if the IANA, in consultation with the media types 970 reviewer, approves, the comment will be made accessible in 971 conjunction with the type registration. 973 5.5. Change Procedures 975 Once a media type has been published by the IANA, the owner may 976 request a change to its definition. The descriptions of the 977 different registration trees above designate the "owners" of each 978 type of registration. The same procedure that would be appropriate 979 for the original registration request is used to process a change 980 request. 982 Media type registrations may not be deleted; media types that are no 983 longer believed appropriate for use can be declared OBSOLETE by a 984 change to their "intended use" field; such media types will be 985 clearly marked in the lists published by the IANA. 987 Significant changes to a media type's definition should be requested 988 only when there are serious omissions or errors in the published 989 specification. When review is required, a change request may be 990 denied if it renders entities that were valid under the previous 991 definition invalid under the new definition. 993 The owner of a media type may pass responsibility to another person 994 or agency by informing the IANA; this can be done without discussion 995 or review. 997 The IESG may reassign responsibility for a media type. The most 998 common case of this will be to enable changes to be made to types 999 where the author of the registration has died, moved out of contact 1000 or is otherwise unable to make changes that are important to the 1001 community. 1003 5.6. Registration Template 1005 Type name: 1007 Subtype name: 1009 Required parameters: 1011 Optional parameters: 1013 Encoding considerations: 1015 Security considerations: 1017 Interoperability considerations: 1019 Published specification: 1021 Applications that use this media type: 1023 Fragment identifier considerations: 1025 Additional information: 1027 Deprecated alias names for this type: 1028 Magic number(s): 1029 File extension(s): 1030 Macintosh file type code(s): 1032 Person & email address to contact for further information: 1034 Intended usage: 1036 (One of COMMON, LIMITED USE or OBSOLETE.) 1038 Restrictions on usage: 1040 (Any restrictions on where the media type can be used go here.) 1042 Author: 1044 Change controller: 1046 Provisional registration? (standards tree only): 1048 (Any other information that the author deems interesting may be 1049 added below this line.) 1050 "N/A", written exactly that way, can be used in any field if desired 1051 to emphasize the fact that it does not apply or that the question was 1052 not omitted by accident. Do not use 'none' or other words that could 1053 be mistaken for a response. 1055 Limited use media types should also note in the applications list 1056 whether or not that list is exhaustive. 1058 6. Structured Syntax Suffix Registration Procedures 1060 Someone wishing to define a "+suffix" name for a structured syntax 1061 for use with a new media type registration SHOULD: 1063 1. Check IANA's registry of media type name suffixes to see whether 1064 or not there is already an entry for that well-defined structured 1065 syntax. 1067 2. If there is no entry for their suffix scheme, fill out the 1068 template (specified in Section 6.2) and include that with the 1069 media type registration. The template may be contained in an 1070 Internet Draft, alone or as part of some other protocol 1071 specification. The template may also be submitted in some other 1072 form (as part of another document or as a stand-alone document), 1073 but the contents will be treated as an "IETF Contribution" under 1074 the guidelines of BCP 78 [RFC5378]. 1076 3. Send a copy of the template or a pointer to the containing 1077 document (with specific reference to the section with the 1078 template) to the mailing list media-types@iana.org, requesting 1079 review. This may be combined with a request to review the media 1080 type registration. Allow a reasonable time for discussion and 1081 comments. 1083 4. Respond to review comments and make revisions to the proposed 1084 registration as needed to bring it into line with the guidelines 1085 given in this document. 1087 5. Submit the (possibly updated) registration template (or pointer 1088 to the document containing it) to IANA at iana@iana.org. 1090 Upon receipt of a structured syntax suffix registration request, 1092 1. IANA checks the submission for completeness; if sections are 1093 missing or citations are not correct, IANA rejects the 1094 registration request. 1096 2. IANA checks the current registry for an entry with the same name; 1097 if such a registry exists, IANA rejects the registration request. 1099 3. IANA requests Expert Review of the registration request against 1100 the corresponding guidelines. 1102 4. The Designated Expert may request additional review or 1103 discussion, as necessary. 1105 5. If Expert Review recommends registration, IANA adds the 1106 registration to the appropriate registry. 1108 6.1. Change Procedures 1110 Registrations may be updated in each registry by the same mechanism 1111 as required for an initial registration. In cases where the original 1112 definition of the scheme is contained in an IESG-approved document, 1113 update of the specification also requires IESG approval. 1115 6.2. Structured Syntax Suffix Registration Template 1117 This template describes the fields that must be supplied in a 1118 structured syntax suffix registration request: 1120 Name 1121 Full name of the well-defined structured syntax. 1123 +suffix 1124 Suffix used to indicate conformance to the syntax. 1126 References 1127 Include full citations for all specifications necessary to 1128 understand the structured syntax. 1130 Encoding considerations 1131 General guidance regarding encoding considerations for any type 1132 employing this syntax should be given here. The same requirements 1133 for media type encoding considerations given in Section 4.8 apply 1134 here. 1136 Interoperability considerations 1137 Any issues regarding the interoperable use of types employing this 1138 structured syntax should be given here. Examples would include 1139 the existence of incompatible versions of the syntax, issues 1140 combining certain charsets with the syntax, or incompatibilities 1141 with other types or protocols. 1143 Fragment identifier considerations 1144 Generic processing of fragment identifiers for any type employing 1145 this syntax should be described here. 1147 Security considerations 1148 Security considerations shared by media types employing this 1149 structured syntax must be specified here. The same requirements 1150 for media type security considerations given in Section 4.6 apply 1151 here, with the exception that the option of not assessing the 1152 security considerations is not available for suffix registrations. 1154 Contact 1155 Person (including contact information) to contact for further 1156 information. 1158 Author/Change controller. 1159 Person (including contact information) authorized to change this 1160 suffix registration. 1162 7. Security Considerations 1164 Security requirements for both media type and media type suffix 1165 registrations are discussed in Section 4.6. 1167 8. IANA Considerations 1169 The purpose of this document is to define IANA registries for media 1170 types and structured syntax suffixes as well as the procedures for 1171 managing these registries. Additionally, this document requires IANA 1172 to maintain a list of IESG-recognized standards bodies who are 1173 allowed to register types in the standards tree. 1175 The existing media type registry has been extended to include a 1176 section for provisional registrations. Only standards tree 1177 registrations are allowed in the standards tree and only at the 1178 request of a standards body on the IESG-recognized standards body 1179 list. See Section 5.2.1 for additional information on provisional 1180 registrations. 1182 The structured syntax name suffix registry is to be created as 1183 follows: 1185 o The name is the "Structured Syntax Suffix" registry. 1187 o The registration process is specified in Section 6. 1189 o The information required for a registry entry as well as the entry 1190 format are specified in Section 6.2. 1192 o The initial content of the registry is specified in 1193 [I-D.appsawg-media-type-suffix-regs]. 1195 Entries in both the media type and structured suffix registries will 1196 be annotated by IANA with both the original registration date as well 1197 as the date of the most recent update to the entry. Registrations 1198 made prior to the implementations of this specification can be marked 1199 as "registered under RFC 4288 or earlier". 1201 Since registration entries can be updated multiple times, IANA is 1202 also requested to maintain the history of changes to each 1203 registration in such a way that the state of the registration at any 1204 given time can be determined 1206 Finally, this document calls for the creation of a new email address, 1207 media-types@iana.org, for the media type review list, which replaces 1208 the ietf-types@iana.org address specified in RFC 4288. 1209 ietf-types@iana.org should be retained as an alias. 1211 9. Acknowledgments 1213 The current authors would like to acknowledge their debt to the late 1214 Dr. Jon Postel, whose general model of IANA registration procedures 1215 and specific contributions shaped the predecessors of this document 1216 [RFC2048] [RFC4288]. We hope that the current version is one with 1217 which he would have agreed but, as it is impossible to verify that 1218 agreement, we have regretfully removed his name as a co-author. 1220 Randy Bush, Bjoern Hoehrmann, Barry Leiba, Murray Kucherawy, Alexey 1221 Melnikov, S. Moonesamy, Mark Nottingham, Tom Petch, Peter Saint- 1222 Andre, and Jeni Tennison provided many helpful review comments and 1223 suggestions. 1225 10. References 1227 10.1. Normative References 1229 [I-D.appsawg-media-type-suffix-regs] 1230 Hansen, T., "Additional Media Type Structured Syntax 1231 Suffixes", draft-appsawg-media-type-suffix-regs-00 (work 1232 in progress), April 2012. 1234 [I-D.ietf-appsawg-mime-default-charset] 1235 Melnikov, A. and J. Reschke, "Update to MIME regarding 1236 Charset Parameter Handling in Textual Media Types", 1237 draft-ietf-appsawg-mime-default-charset-01 (work in 1238 progress), March 2012. 1240 [RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail 1241 Extensions (MIME) Part One: Format of Internet Message 1242 Bodies", RFC 2045, November 1996. 1244 [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail 1245 Extensions (MIME) Part Two: Media Types", RFC 2046, 1246 November 1996. 1248 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1249 Requirement Levels", BCP 14, RFC 2119, March 1997. 1251 [RFC2978] Freed, N. and J. Postel, "IANA Charset Registration 1252 Procedures", BCP 19, RFC 2978, October 2000. 1254 [RFC3023] Murata, M., St. Laurent, S., and D. Kohn, "XML Media 1255 Types", RFC 3023, January 2001. 1257 [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 1258 10646", STD 63, RFC 3629, November 2003. 1260 [RFC3979] Bradner, S., "Intellectual Property Rights in IETF 1261 Technology", BCP 79, RFC 3979, March 2005. 1263 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 1264 Resource Identifier (URI): Generic Syntax", STD 66, 1265 RFC 3986, January 2005. 1267 [RFC4855] Casner, S., "Media Type Registration of RTP Payload 1268 Formats", RFC 4855, February 2007. 1270 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 1271 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 1272 May 2008. 1274 [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax 1275 Specifications: ABNF", STD 68, RFC 5234, January 2008. 1277 [RFC5378] Bradner, S. and J. Contreras, "Rights Contributors Provide 1278 to the IETF Trust", BCP 78, RFC 5378, November 2008. 1280 [RFC6532] Yang, A., Steel, S., and N. Freed, "Internationalized 1281 Email Headers", RFC 6532, January 2012. 1283 10.2. Informative References 1285 [I-D.ietf-appsawg-xdash] 1286 Saint-Andre, P. and D. Crocker, "Deprecating the X- Prefix 1287 and Similar Constructs in Application Protocols", 1288 draft-ietf-appsawg-xdash-05 (work in progress), 1289 April 2012. 1291 [MacOSFileTypes] 1292 Apple Computer, Inc., "Mac OS: File Type and Creator 1293 Codes, and File Formats", Apple Knowledge Base Article 1294 55381, June 1993, 1295 . 1297 [RFC2026] Bradner, S., "The Internet Standards Process -- Revision 1298 3", BCP 9, RFC 2026, October 1996. 1300 [RFC2048] Freed, N., Klensin, J., and J. Postel, "Multipurpose 1301 Internet Mail Extensions (MIME) Part Four: Registration 1302 Procedures", BCP 13, RFC 2048, November 1996. 1304 [RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded 1305 Word Extensions: 1306 Character Sets, Languages, and Continuations", RFC 2231, 1307 November 1997. 1309 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., 1310 Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext 1311 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. 1313 [RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and 1314 Registration Procedures", BCP 13, RFC 4288, December 2005. 1316 [RFC5987] Reschke, J., "Character Set and Language Encoding for 1317 Hypertext Transfer Protocol (HTTP) Header Field 1318 Parameters", RFC 5987, August 2010. 1320 Appendix A. Grandfathered Media Types 1322 A number of media types with unfaceted subtype names, registered 1323 prior to 1996, would, if registered under the guidelines in this 1324 document, be given a faceted name and placed into either the vendor 1325 or personal trees. Reregistration of those types to reflect the 1326 appropriate trees is encouraged but not required. Ownership and 1327 change control principles outlined in this document apply to those 1328 types as if they had been registered in the trees described above. 1330 From time to time there may also be cases where a media type with an 1331 unfaceted subtype name has been widely deployed without being 1332 registered. (Note that this includes subtype names beginning with 1333 the "x-" prefix.) If possible such media type SHOULD be reregistered 1334 with a proper faceted subtype name. However, if this is not possible 1335 the type can, subject to approval by both the media types reviewer 1336 and the IESG, be registered in the proper tree with its unfaceted 1337 name. 1339 Appendix B. Changes Since RFC 4288 1341 o Suffixes to indicate the use of a particular structured syntax are 1342 now fully specified and a suffix registration process has been 1343 defined. 1345 o Registration of widely deployed unregistered unfaceted type names 1346 in the vendor or personal trees is now allowed, subject to 1347 approval by the media types reviewer and the IESG. 1349 o The standards tree registration process has been revised to 1350 include Expert Review and generalized to address cases like media 1351 types in non-IETF stream documents. 1353 o A field for fragment identifiers has been added to the 1354 registration template and brief directions for specifying fragment 1355 identifiers have been added. 1357 o The specification requirements for personal tree registrations 1358 have been changed to be the same as those for the vendor tree. 1359 The text has been changed to encourage (but not require) 1360 specification availability. 1362 o The definition of additional trees has been clarified to state 1363 that an IETF Standards Action is required. 1365 o Widely deployed types with "x-" names can now be registered as an 1366 exception in the vendor tree. 1368 o The requirements on changes to registrations have been loosened so 1369 minor changes are easier to make. 1371 o The registration process has been completely restructured so that 1372 with the exception of IETF-generated types in the standards tree, 1373 all requests are processed by IANA and not the IESG. 1375 o A provisional registration process has been added for early 1376 assignment of types in the standards tree. 1378 o Many editorial changes have been made throughout the document to 1379 make the requirements and processes it describes clearer and 1380 easier to follow. 1382 o The ability to specify a list of deprecated aliases for a media 1383 type has been added. 1385 o Types with names beginning with "x-" are no longer considered to 1386 be members of the unregistered "x." tree. As with any unfaceted 1387 type, special procedures have been added to allow registration of 1388 such types in an appropriate tree. 1390 o Changes to a type registered by a third party may now be made by 1391 the designated change controller even if that isn't the vendor or 1392 organization that created the type. However, the vendor or 1393 organization may elect to assert ownership and change controller 1394 over the type at any time. 1396 o Limited use media types are now asked to note whether or not the 1397 supplied list of applications employing the media type is 1398 exhaustive. 1400 o The ABNF for media type names has been further restricted to 1401 require that names begin with an alphanumeric character. 1403 o Mailing list review is no longer required prior to registration of 1404 media types. Additionally, the address associated with the media 1405 type review mailing list has been changed to media-types@iana.org. 1407 o The rules for text/* media types have been updated to reflect the 1408 changes specified in [I-D.ietf-appsawg-mime-default-charset]. 1410 Authors' Addresses 1412 Ned Freed 1413 Oracle 1414 800 Royal Oaks 1415 Monrovia, CA 91016-6347 1416 USA 1418 Email: ned+ietf@mrochek.com 1419 John C. Klensin 1420 1770 Massachusetts Ave, #322 1421 Cambridge, MA 02140 1422 USA 1424 Email: john+ietf@jck.com 1426 Tony Hansen 1427 AT&T Laboratories 1428 200 Laurel Ave. 1429 Middletown, NJ 07748 1430 USA 1432 Email: tony+mtsuffix@maillennium.att.com