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(See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (December 14, 1998) is 9264 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Possible downref: Non-RFC (?) normative reference: ref. 'SI' Summary: 9 errors (**), 0 flaws (~~), 3 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 INTERNET-DRAFT Larry Masinter 2 draft-ietf-conneg-media-features-03.txt Koen Holtman 3 Andy Mutz 4 Dan Wing 5 expires in 6 months December 14, 1998 7 Media Features for Display, Print, and Fax 9 Status of this memo 11 This document is an Internet-Draft. Internet-Drafts are working 12 documents of the Internet Engineering Task Force (IETF), its areas, 13 and its working groups. Note that other groups may also distribute 14 working documents as Internet-Drafts. 16 Internet-Drafts are draft documents valid for a maximum of six 17 months and may be updated, replaced, or obsoleted by other 18 documents at any time. It is inappropriate to use Internet-Drafts 19 as reference material or to cite them other than as "work in 20 progress." 22 To view the entire list of current Internet-Drafts, please check 23 the "1id-abstracts.txt" listing contained in the Internet-Drafts 24 Shadow Directories on ftp.is.co.za (Africa), ftp.nordu.net 25 (Northern Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au 26 (Pacific Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu 27 (US West Coast). 29 Copyright (C) The Internet Society (1997). All Rights Reserved. 31 Abstract 33 This specification defines some common media features for 34 describing image resolution, size, color, and image representation 35 methods that are common to web browsing, printing, and facsimile 36 applications. These features are registered for use within the 37 framework of [REG]. 39 1. Introduction 41 This work was originally motivated by the requirements from web 42 browsers to send the browser's display characteristics to the web 43 server to allow the server to choose an appropriate representation. 45 This specification defines some common media features [REG] by 46 which a recipient may inform a sender as to the characteristics of 47 its message handling. The sender may then provide the variant of 48 the message that is most suitable for the recipient. 50 Different variants would typically be higher or lower resolution 51 images (for example) as appropriate. In the case of a sending to a 52 printer, the result would be higher quality output. In the case of 53 a small screen device (cellphone, portable digital assistant), the 54 result would be faster transmission. 56 Media features may be used in many different protocol situations. 57 Those defined in this specification can indicate the display or 58 printer dimensions, resolution, color capability. The physical 59 dimensions of a display may be inferred from the display size and 60 display resolution. In the case of paper output, the paper size may 61 be expressed as a token from a list of standard paper sizes. These 62 are presented formally in the Notation section. 64 2. Media Feature Registrations 66 This section defines several media features, using the form 67 specified in [REG]. 69 2.1 Image Size 71 - Media Feature tag name(s): 73 pix-x 74 pix-y 76 - ASN.1 identifier associated with this feature tag: 78 ***New assignments by IANA*** 80 - Summary of the media features indicated by this feature tag: 82 These features indicate the display size of the recipient for 83 display or print, measured in pixels; they indicate horizontal 84 (pix-x) and vertical (pix-y) dimensions. 86 - Values appropriate for use with this feature tag: 88 Signed Integer 90 - The feature tag is intended primarily for use in the following 91 applications, protocols, services, or negotiation mechanisms: 93 Display and print applications where different media choices will 94 be made depending on the size of the recipient device. For 95 example, a web application for use on a 240x480 display might use 96 different HTML pages than one intended for use on a 1024x768 97 display. 99 2.2 Resolution 101 - Media Feature tag name: 103 dpi 105 - ASN.1 identifier associated with this feature tag: 107 ***New assignments by IANA*** 109 - Summary of the media features indicated by this feature tag: 111 This feature indicates the resolution that the recipient can 112 display or print without loss, measured in pixels per inch. 113 Typically resolution capability is represented as dots-per-inch 114 rather than in SI units [SI]. Values for dpi may be expressed as a 115 rational to accomodate resolution of SI-based devices; for example 116 dpi=19558/100 can be used to represent a resolution of 77 dots per 117 centimeter. 119 - Values appropriate for use with this feature tag: 121 Rational 123 - The feature tag is intended primarily for use in the following 124 applications, protocols, services, or negotiation mechanisms: 126 Printing and fax applications typically choose representations of 127 a transmitted document depending on the resolution of the 128 recipient rather than pixel size. 130 - Examples of typical use: 132 Choosing a version of a printable document to send to a printer. 134 - Considerations particular to use in individual applications, 135 protocols, services, or negotiation mechanisms: 137 Software applications are typically unaware of the resolution of 138 the display. Note that there exist devices with different 139 resolution in different directions, i.e., individual pixels are 140 not square. However, this feature only encompasses. 142 2.3 Registration of 'ua-media' 144 - Media Feature tag name(s): 146 ua-media 148 - ASN.1 identifier associated with this feature tag: 150 ***New assignments by IANA*** 152 - Summary of the media features indicated by this feature tag: 154 This feature indicates the recipients device media, indicated with 155 an simple token. 157 - Values appropriate for use with this feature tag: 159 Token with an equality relationship. Typical values include: 161 screen A refreshable display 162 screen-paged a refreshable display which cannot scroll 163 stationery Separately cut sheets of an opaque material 164 transparency Separately cut sheets of a transparent material 165 envelope Envelopes that can be used for conventional 166 mailing purposes 167 envelope-plain Envelopes that are not preprinted and have no 168 windows 169 continuous Continuously connected sheets of an opaque 170 material 172 - The feature tag is intended primarily for use in the following 173 applications, protocols, services, or negotiation mechanisms: 175 Most of the feature values are useful for printing applications, 176 or to distinguish printing from display. 178 - Examples of typical use: 180 This might typically be used for selecting between a rendition 181 that is intended to be printed and one that is intended to be 182 displayed. 184 - Considerations particular to use in individual applications, 185 protocols, services, or negotiation mechanisms: 187 Other media values were not included because their utility seemed 188 relative. 190 - Interoperability considerations: 192 Interoperability with the Internet Print Protocol means that 193 some additional feature values may need to be registered. 195 2.4 Paper Size 197 - Media Feature tag name(s): 199 paper-size 201 - ASN.1 identifier associated with this feature tag: 203 ***New assignment by IANA*** 205 - Summary of the media features indicated by this feature tag: 207 For stationery, it is often useful to have information about the 208 size of display used. While it is more precise and predictable to 209 use absolute resolution and pixel sizes, some applications find it 210 useful to provide paper size in addition to this information. Note 211 that not all of the paper may have a printable area. 213 - Values appropriate for use with this feature tag: 215 String with equality 217 letter: 8.5x11.0 inches 218 A4: 210x297 mm 219 B4: 250x353 mm 220 A3: 297x420 mm 221 legal: 8.5x14 inches 223 - The feature tag is intended primarily for use in the following 224 applications, protocols, services, or negotiation mechanisms: 226 This feature tag seems most useful for the printing application. 228 - Examples of typical use: 230 Choosing between a4 and letter size renditions of the same 231 printable document. 233 2.5 Color and greyscale 235 - Media Feature tag name(s): 237 color 239 - ASN.1 identifier associated with this feature tag: 241 ***New assignments by IANA*** 243 - Summary of the media features indicated by this feature tag: 245 This feature indicates a gross level of capability to represent 246 (or need for) for handling of color, out of a limited set of 247 choices. 249 - Values appropriate for use with this feature tag: 251 Token with an equality relationship. Values include: 253 binary black-and-white, or other bi-level capability. 255 grey more than two levels of intensity; for example, 256 at least two bits of grey-scale data 258 limited availability of a small number of colors, such as 259 might be provided by a highlight printer, pen plotter, 260 or limited color display. Such capability is useful 261 for business graphics. At the lowest level of 262 capability, this implies at least one color other than 263 black ("highlight color"). At the high end, a small 264 number (less than 32) colors. No implication is made 265 that any particular color is available. 267 mapped 268 pixel color values are mapped in some specifable way 269 to a multi-component color space. Sufficient levels of 270 display are available to represent a continuous tone 271 photographic image, but the result will be mapped into 272 a more limited space. 274 full ability (or at least willingness) to represent a full 275 color image and present it. Full continuous tone color 276 capability. 278 - The feature tag is intended primarily for use in the following 279 applications, protocols, services, or negotiation mechanisms: 281 Web applications may choose between color, grey, or binary 282 representations. Fax or printing applications might choose 283 between color and non-color renditions, for example. 285 - Examples of typical use: 287 Someone preparing a map of directions to a restaurant might 288 prepare different maps for each kind of value. 290 - Related standards or documents: 292 n/a 294 - Considerations particular to use in individual applications, 295 protocols, services, or negotiation mechanisms: 297 n/a 299 - Interoperability considerations: 301 n/a 303 - Security considerations: 305 n/a 307 - Privacy concerns, related to exposure of personal information: 309 n/a 311 - Denial of service concerns related to consequences of specifying 312 incorrect values: 314 n/a 316 - Additional information: 318 n/a 320 - Keywords: 322 n/a 323 - Related feature tags: 325 - Related media types or data formats: 327 - Related markup tags: 329 - Name(s) & email address(es) of person(s) to contact for 330 further information: 332 - Intended usage: 333 COMMON 335 - Author/Change controller: 337 3. Examples of use of features 339 The following examples of feature comparison show how these features 340 can be used to describe various capabilities. The syntax used to 341 express combinations of features is purely illustrative and not 342 normative: 344 pix-x<=1024, pix-y<=768 345 indicates a 1024x768 display 347 dpi<=72 348 indicates a 72 dpi display 350 ua-media=stationery 351 indicates the display is a cut sheet of opaque material, such as 352 paper. 354 paper-size=iso-a4 355 indicates the display size is 210x297mm. 357 color<=24 358 indicates the display supports 24-bit (8-bit/channel) color. 360 4. IANA considerations 362 This document calls for registration of the following feature tags, 363 as per [REG]: pix-x, pix-y, dpi, ua-media, paper-size, color. 364 ASN.1 identifiers should be assigned to each of these and replaced 365 in the body of the registration. 367 5. Acknowledgments 369 This document is based on a previous draft co-authored with Lou 370 Montoulli. It had benefited from the comments of Graham Klyne, Ho 371 John Lee, Brian Behlendorf, Jeff Mogul, and Ted Hardie. 373 6. References 375 [REG] A. Mutz, T. Hardie. "Feature Tag Registration Procedures", 376 draft-ietf-conneg-feature-reg-03.txt, July 1998. 378 [SI] ISO 1000:1992 "SI units and recommendations for the use of 379 their multiples and of certain other units", International 380 Organization for Standardization, 1992. 382 Author's Addresses 384 Larry Masinter 385 Xerox Palo Alto Research Center 386 3333 Coyote Hill Road 387 Palo Alto CA 94304 388 Fax +1 415 812 4333 389 Email: masinter@parc.xerox.com 391 Dan Wing 392 Cisco Systems, Inc. 393 101 Cooper Street 394 Santa Cruz, CA 95060 USA 395 Phone: +1 408 457 5200 396 Fax: +1 408 457 5208 397 EMail: dwing@cisco.com 399 Andrew H. Mutz 400 Hewlett-Packard Company 401 1501 Page Mill Road 3U-3 402 Palo Alto CA 94304, USA 403 Fax +1 415 857 4691 404 Email: mutz@hpl.hp.com 406 Koen Holtman 407 Technische Universiteit Eindhoven 408 Postbus 513 409 Kamer HG 6.57 410 5600 MB Eindhoven (The Netherlands) 411 Email: koen@win.tue.nl