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XHTMLTM-Print

Printer Working Group Proposed Standard 5102.1 Working Draft, February 10, 2003

March 31, 2003

This version:
http://www.pwg.org/xhtml-print/HTML-Version/XHTML-Print.html
Latest version:
http://www.pwg.org/xhtml-print/HTML-Version/XHTML-Print.html
PDF Version:
http://www.pwg.org/xhtml-print/HTML-Version/XHTML-Print.pdf
Markup Version:
http://www.pwg.org/xhtml-print/HTML-Version/XHTML-PrintWithMarkup-20030331.html
Previous version:
http://www.pwg.org/xhtml-print/HTML-Version/XHTML-Print-20030210.html
Editors:
Don Wright, Lexmark International
Melinda Grant, HP
Peter Zehler, Xerox
Jun Fujisawa, Canon
Jim Bigelow, Hewlett-Packard Co.
Elliott Bradshaw, Oak Technology Imaging Group

Abstract

HTML 4 is a powerful language for authoring Web content, but its design does not take into consideration issues pertinent to printers, including the implementation cost (in power, memory, etc.) of the full feature set. Printers have relatively limited resources that cannot generally afford to implement the full feature set of HTML 4.

Because there are many ways to subset HTML, there are many almost identical subsets defined by organizations and companies. Without a common base set of features, developing print applications for a wide range of printers is difficult.

XHTML-Print's targeted usage is for printing in environments where it is not feasible or desirable to install a printer-specific driver and where some variability in the formatting of the output is acceptable.

The document type definition for XHTML-Print is implemented based on the XHTML modules defined in Modularization of XHTML [XHTMLMOD].

Status of this Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. The latest status of this document series is maintained at the PWG.

All sections of this document are normative unless noted as informative.

This document may be copied and furnished to others, and derivative works that comment on, or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice, this paragraph and the title of the Document as referenced below are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the IEEE-ISTO and the Printer Working Group, a program of the IEEE-ISTO.

Title: The Printer Working Group Proposed Standard XHTML-Print

The IEEE-ISTO and the Printer Working Group DISCLAIM ANY AND ALL WARRANTIES, WHETHER EXPRESS OR IMPLIED INCLUDING (WITHOUT LIMITATION) ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

The Printer Working Group, a program of the IEEE-ISTO, reserves the right to make changes to the document without further notice. The document may be updated, replaced or made obsolete by other documents at any time.

The IEEE-ISTO takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights.

The IEEE-ISTO invites any interested party to bring to its attention any copyrights, patents, or patent applications, or other proprietary rights which may cover technology that may be required to implement the contents of this document. The IEEE-ISTO and its programs shall not be responsible for identifying patents for which a license may be required by a document and/or IEEE-ISTO Industry Group Standard or for conducting inquiries into the legal validity or scope of those patents that are brought to its attention. Inquiries may be submitted to the IEEE-ISTO by email at: ieee-isto@ieee.org.

The Printer Working Group acknowledges that the IEEE-ISTO (acting itself or through its designees) is, and shall at all times, be the sole entity that may authorize the use of certification marks, trademarks, or other special designations to indicate compliance with these materials.

Use of this document is wholly voluntary. The existence of this document does not imply that there are no other ways to produce, test, measure, purchase, market, or provide other goods and services related to its scope.

This document is a working draft and only a working draft. It is currently being reviewed by PWG Members but has not been approved. It is not a stable document and may not be used as reference material nor cited as a normative reference from another document.

Public discussion of XHTML-Print takes place on the mailing list: xp@pwg.org ( archive). To subscribe send an email to majordomo@pwg.org with the words subscribe xp in the body. You must be subscribed to the mailing list to post there. Please report errors in this document to one of the editors listed above or on the mailing list.

A list of current PWG Standards and other technical documents can be found at http://www.pwg.org/standards.html

Note: The following review conventions are used in this document:

Table of Contents

1. Introduction

1.1. XHTML for Printing

This section is informative.

This document specifies a simple XHTML based data stream suitable for printing as well as display. It is based on the W3C's XHTML Basic [XHTMLBASIC] with the addition of cascading style sheets (CSS) [CSSPP] . Its targeted usage is for printing in environments where it is not feasible or desirable to install a printer-specific driver and where some variability in the formatting of the output is acceptable. Throughout this document this data stream is called "XHTML-Print."

XHTML-Print is designed to be appropriate for low-cost printers that may not have a full-page buffer and that generally print from top-to-bottom and left-to-right with the paper in a portrait orientation. For other printers (i.e., those that print in another direction or orientation) a full-page buffer may be required.

XHTML-Print is not appropriate when strict layout consistency and repeatability across printers are required. The design objective of XHTML-Print is to provide a relatively simple, broadly supportable page description format where content preservation and reproduction are the goal, i.e. "Content is King." Traditional printer page description formats such as PostScript or PCL are more suitable when strict layout control is required. XHTML-Print does not utilize bi-directional communications with the printer either for capabilities or status inquiries.

This document creates a set of conformance criteria for XHTML-Print. It references style sheet constructs drawn from CSS2 [CSS2] and proposed for CSS3 [CSS3] as defined in the CSS Print Profile [CSSPP] to provide a strong basis for rich printing results without a detailed understanding of each individual printer's characteristics.

It also defines an extension set that provides stronger layout control for the printing of mixed text and images, tables and image collections.

The document type definition for XHTML-Print is implemented based on the XHTML modules defined in Modularization of XHTML [XHTMLMOD].

1.2. Terminology

The keywords "MUST", "SHALL", "MUST NOT", "SHALL NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" when used in this document are to be interpreted as described in RFC 2119 [RFC2119]. However, for readability, these words do not appear in all uppercase letters in this specification.

1.3. Design Rationale

This section explains why certain HTML features are not part of XHTML-Print.

1.3.1. Script and Events

The script and noscript elements are not supported as a printer lacks typical user interaction necessary for a script.  Content of the script should not be printed.

Events are not applicable to static, printed versions of a document. Therefore, the Intrinsic Events module is not part of XHTML-Print.

1.3.2. Presentation

Many simple printers cannot print a wide variety of fonts other than the generic serif, san serif and monospace. It is recommended that style sheets be used to create a presentation that is appropriate for a particular category of printer. How printers are categorized, what those categories are, how a printer identifies itself as a member of a category, and how style sheets are selectively applied based on category, is outside the scope of this document.

The Presentation module, section 5.4.1 of [XHTMLMOD] is supported since it allows a very simple user agent to support font variants. The module contains elements that are both structural and presentational, provides the only method for specifying rules (the hr element), and allows very simple clients that might not support CSS the means for identifying font variants such as bold, italic, superscript and subscript. Supporting this module allows a client to render these common elements in a manner that is appropriate for its capabilities.

1.3.3. Forms

Basic XHTML forms, section 5.5.1 [XHTMLMOD] are supported. Content developers should keep in mind that users may not be able to input many characters from some devices (e.g. from a mobile phone). Note that a printer prints a static version of a form, and the visual appearance of a form depends heavily on the implementation.

1.3.4. Tables

Basic XHTML tables, section 5.6.1 [XHTMLMOD] are supported, but tables can be difficult to format on very low resourced devices.  Note that in the Basic Tables Module, nesting of tables is prohibited.

1.3.5. Frames

Frames are not supported. Frames depend on a screen interface and therefore are not applicable to printers.

1.3.6. Attributes

XHTML-Print is a member of the family of XHTML languages defined by [XHTMLMOD]. Therefore, the elements and attributes in the modules that make up XHTML-Print are all valid constructs of the language. However, not all the attributes are applicable to a rendering of an XHTML-Print document in a printed media, especially those that are integral to a dynamic display of the document in a browser and the submission of a form. Furthermore, special attention is given to simple printers and some attributes are deemed too complex for a such a printer to render. These attributes are treated as discretionary in that a conforming printer is not required to support them, but should a printer wish to provide that support there are requirements stated for consistency in the implementation of extensions.

2. Conformance

2.1. Document Conformance

A conforming XHTML-Print document is a document that requires only the facilities described as mandatory in this specification. Such a document shall meet all of the following criteria:

  1. The document shall validate against the DTD found in Appendix C and conform to the constraints expressed in Design Rationale.
  2. The root element of the document shall be <html>.
  3. The name of the default namespace on the root element shall be the XHTML namespace name, http://www.w3.org/1999/xhtml.
  4. There shall be a DOCTYPE declaration in the document prior to the root element. If present, the public identifier included in the DOCTYPE declaration shall reference the DTD found in Appendix C using its Formal Public Identifier. The system identifier may be modified appropriately.

  5. <!DOCTYPE html PUBLIC "-//PWG//DTD XHTML-Print 1.0//EN"
    "http://www.xhtml-print.org/xhtml-print/xhtml-print10.dtd">
     
  6. The DTD subset must not be used to override any parameter entities in the DTD.

The MIME type used to refer to a conforming XHTML-Print document shall be "application/vnd.pwg-xhtml-print+xml".  An optional "charset" parameter may be provided with the MIME type.  Usage of the optional "charset" parameter is as described in section 3.2 of [RFC3023]. 

Additionally, printers may support a MIME type of "application/xhtml+xml" with a profile of "http://www.xhtml-print.org/xhtml-print/xhtml-print10.dtd".  Not all printers will support this option, therefore clients cannot always depend upon it.  Use of a profile is as described in section 2 and section 8 of [RFC3236].

2.2. Client Conformance

  1. Clients shall produce a well-formed XHTML-Print document as defined in XHTML 1.0 [XHTML1] and in Document Conformance.
  2. Beyond number 1 above, clients are not required to use more of the XHTML-Print elements or Style Sheet attributes than necessary to get the desired output.

2.3 Printer Conformance

2.3.1 Formatting/Rendering Rules

A printer must conform to the XHTML Family User Agent Conformance section of the "Modularization of XHTML" specification ([XHTMLMOD],section 3.5) with the following exceptions and additions:
  1. Validation is not required to claim conformance to this standard. A printer may flush or otherwise reject a non-conforming XHTML-Print document.
  2. Images:
  3. Printers may choose not to render content within elements defined by XHTML [XHTML1] or HTML [HTML4] that are obviously not intended to be rendered, e.g. <script>.
  4. A Form Feed character (&000C;) must be treated as whitespace.
  5. Printers that do not support the xml:lang attribute are not required to adhere to the rules for language specific whitespace handling.

2.3.2 XHTML Requirements

  1. A conforming printer shall support all XHTML Modules listed in The XHTML-Print Document Type.
  2. A conforming printer shall print a static version of a form using default and selected values as specified in the form.
  3. Printers supporting inline image data shall support [MIMEMPX] as described in Appendix B.
  4. A conforming printer shall identify this datastream by the exact string: "XHTML-Print" (without the quotation marks) in all service discovery records and protocols, device identification records and protocols, and in other cases where a list of supported datastreams is to be presented by the printer.  Where such datastreams are identified by a MIME media type, the string "application/vnd.pwg-xhtml-print+xml" shall be used.
  5. A conforming printer shall support the CSS constructs and associated values given in the CSS Print Profile[CSSPP]; support for other values and other properties or constructs is optional.

2.4. Enhanced Layout Extension Conformance

To further support print applications requiring more exacting page layout (e.g., photo album pages), the style sheet properties of the Enhanced Layout Extension of the CSS Print Profile ([CSSPP] section 2.1) and image processing (Appendix A.3) shall be supported in an optional, discoverable (via some means outside the scope of this document) Enhanced Layout Extension.

The following is an informative example using absolute positioning with image data:


<style>
.picture1 {
     position: absolute;
     top: 25mm;
     left: 25mm;
     padding-top: 10mm;
     width: 30mm;
     height: 30mm;
     clip: rect(10mm, 30mm, 30mm, 0mm)
          }
</style>
. . .
<div class="picture1">
<img src="some_file.jpg" />
</div>
 

3. The XHTML-Print Document Type

The XHTML-Print document type is defined as a set of XHTML modules. All XHTML modules are defined in the "Modularization of XHTML" specification [XHTMLMOD].

XHTML-Print consists of the following XHTML modules:

Structure Module*
body, head, html, title
Text Module*
abbr, acronym, address, blockquote, br, cite, code, dfn, div, em, h1, h2, h3, h4, h5, h6, kbd, p, pre, q, samp, span, strong, var
Hypertext Module*
a
List Module*
dl, dt, dd, ol, ul, li
Text Extension Module - Presentation**
b, big, hr, i, small, sub, sup, tt
Basic Forms Module
form, input, label, select, option, textarea
Basic Tables Module
caption, table, td, th, tr
Image Module
img
Object Module
object, param
Metainformation Module
meta
Style Sheet Module**
style
Style Attribute Module**
style attribute
Link Module
link
Base Module
base

(*) = This module is a required XHTML Host Language module.
(**) = These modules are not a part of XHTML Basic but are required for XHTML-Print.

An XML 1.0 DTD is available in Appendix C.

NOTE: Since the HTML event handler attributes are not included in XHTML-Print, form controls outside forms may not function as expected by the user.

3.1 Attributes and Attribute Collections

HTML allows binary attributes to be given without a value, e.g. <option selected>. However, XML, and hence XHTML 1.0 languages, requires all attributes to take a value. Thus in XHTML-Print these shall be given with a cloned value (e.g. selected="selected").

Some of the attributes defined in [XHTMLMOD] are not applicable to the printed page or are not relevant due to the exclusion of their module from XHTML-Print. Other attributes have equivalent CSS properties that when present take precedence over the attribute. Other attributes are not required but if supported by a printer, support should be provided in the recommended manner.

Each attribute in the following sections is annotated to indicate how it should be treated by a conforming printer:

Key Description
Yes Support is manditory; a conforming printer must honor this attribute;
No Support is optional; a conforming printer may ignore this attribute for one of the following reasons, but cannot treat it as an error:
  • The attribute applies to a user interface which is not represented on a printed page.
  • The attribute applies to form submission which is not performed by the printer.
  • The attribute describes data which is not represented on a printed page.
  • The attribute applies to objects other than JPEG images, such as java applets.
  • The attribute is not needed because the document character set is restricted to UTF-8.
  • The attribute is part of functionality that is deemed too complex for low cost printers, such as language specific processing, printing on landscape oriented pages, buffering of images for later use, and vertical alignment of cell data in tables that span multiple pages.

The Modularization of XHTML ([XHTMLMOD], section 5.1) contains a set of attribute collections for ease of presentation. This specification continues this practice with the same conditions as in [XHTMLMOD], that the collections are informative and their contents normative.

Collection Name Attributes in Collection Supported
Coreclass (NMTOKENS )Yes
id (ID)Yes
title (CDATA)No
I18Nxml:lang (NMTOKEN)No
Stylestyle (CDATA)Yes
CommonCore + I18N + StyleSee Collections

Table Note:

† See [XHTMLMOD],section 4.3

Note that the title attribute of the Core collection is not applicable to the printed page since there is no place to display such supplementary information.

Note that support for the xml:lang attribute is optional, if a printer supports special processing based on the spoken language of the document, that processing shall be controlled by this attribute.

3.2 Structure Module

Elements Attributes Supported
bodyCommon See Collection
headI18N, See Collection
profile (URI)No
htmlI18N, See Collection
version (CDATA), Yes
xmlns (URI = "http://www.w3.org/1999/xhtml")Yes
titleI18N See Collection

Table Note:

† See [XHTMLMOD],section 4.3

If the printer implements support for meta data then it must support the profile attribute of the head element.

3.3 Text Module

Elements Attributes Supported
abbr, acronym, addressCommon See Collection
blockquoteCommon, See Collection
cite (URI)No
brCore See Collection
cite, code, dfn, div, em, h1, h2, h3, h4, h5, h6, kbd, pCommon See Collection
pre Common, See Collection
xml:space="preserve" Yes
q Common, See Collection
cite (URI) No
samp, span, strong, var Common See Collection

Table Note:

† See [XHTMLMOD],section 4.3

The CSS white-space property is preferred over the xml:space attribute, since the attribute is an internal mechanism between the XML processor and the formatting application and doesn't directly control the formatting of the output.

3.4 Hypertext Module

Element Attributes Supported
a Common, See Collection
accesskey (Character), No
charset (Charset), No
href (URI), No
hreflang (LanguageCode), No
rel (LinkTypes), No
rev (LinkTypes), No
tabindex (Number), No
type (ContentType)No

Table Note:

† See [XHTMLMOD],section 4.3

3.5 List Module

Elements Attributes Supported
dl, dt, dd, ol, ul, li Common See Collection

3.6 Presentation Module

Elements Attributes Supported
b, big, hr, i, small, sub, sup, tt Common See Collection

Table Note:

See [XHTMLMOD],section 4.3

3.7 Basic Forms Module

Elements Attributes Supported
form Common, See Collection
action* (URI), No
method ("get"** | "post"), No
enctype (ContentType) No
input Common, See Collection
accesskey (Character), No
checked ("checked"), Yes
maxlength (Number), No
name (CDATA), No
size (Number), Yes
src (URI), No
tabindex (Number), No
type("text"** |Yes
"password" |Yes
"checkbox" |Yes
"radio" | Yes
"submit" | Yes
"reset" | Yes
"hidden" ) No
value (CDATA)Yes
label Common, See Collection
accesskey (Character), No
for (IDREF)No
select Common, See Collection
multiple ("multiple"), No
name (CDATA), No
size (Number), Yes
tabindex (Number)No
option Common, See Collection
selected ("selected"), Yes
value (CDATA)Yes
textarea Common, See Collection
accesskey (Character), No
cols* (Number), Yes
name (CDATA), No
rows* (Number), Yes
tabindex (Number) No

Table Notes:

† See [XHTMLMOD],section 4.3

* The attribute must be present.

** The value is the default.

3.8 Basic Tables Module

Elements Attributes Supported
caption Common See Collection
table Common, See Collection
summary ( Text ) No
td Common, See Collection
abbr (Text), No
align ("left" | "center" | "right"), Yes
axis (CDATA), No
colspan (Number), Yes
headers (IDREFS), No
rowspan (Number), Yes
scope ("row" | "col"), No
valign ("top" | "middle" | "bottom")Yes
th Common, See Collection
abbr (Text), No
align ("left" | "center" | "right"), Yes
axis (CDATA), No
colspan (Number), Yes
headers (IDREFS), No
rowspan (Number), Yes
scope ("row" | "col"), No
valign ("top" |"middle" | "bottom")Yes
tr Common, See Collection
align ("left" | "center" | "right"), Yes
valign ("top" | "middle" | "bottom")Yes

Table Note:

† See [XHTMLMOD],section 4.3

If a printer implements a feature to truncate the contents of a cell because of space constraints, it must support the abbr attribute so that it may print the value of the abbr attribute (if present) instead of the cell's content.

Vertical alignment is undefined across page boundaries.

3.9 Image Module

Elements Attributes Supported
img Common, See Collection
alt* (Text), Yes
height (Length), Yes
longdesc (URI), No
src* (URI), Yes
width (Length)Yes

Table Notes:

† See [XHTMLMOD],section 4.3

* The attribute must be present.

3.10 Object Module

Elements Attributes Supported
object Common, See Collections
archive (URIs), No
classid (URI), No
codebase (URI), Yes
codetype (ContentType), No
data (URI), Yes
declare ("declare"), No
height (Length), Yes
name (CDATA), No
standby (Text), No
tabindex (Number), No
type ("image/jpeg"), Yes
width (Length)Yes
param id (ID), No
name* (CDATA), No
type (ContentType), No
value (CDATA), No
valuetype ("data"** | "ref" | "object")No

Table Notes:

† See [XHTMLMOD],section 4.3

* The attribute must be present.

** The value is the default.

If the printer implements object storage then the declare attribute of the object element must be supported.

The param element's purpose is to pass data to an application specified in the enclosing object element. Since only images, which don't need initialization, are supported in the object element, this element can be completely ignored.

3.11 Metainformation Module

Elements Attributes Supported
meta I18N, See Collection
content* (CDATA), No
http-equiv (NMTOKEN), No
name (NMTOKEN), No
scheme (CDATA)No

Table Notes:

† See [XHTMLMOD],section 4.3

* The attribute must be present.

If the printer implements support for features of this element, the http-equiv attribute must be supported.

3.12 Style Sheet Module

Elements Attributes Supported
style I18N, See Collection
media (MediaDesc), Yes
title (Text), No
type* ("type/css"), Yes
xml:space="preserve"Yes

Table Notes:

† See [XHTMLMOD],section 4.3

* The attribute must be present.

The CSS white-space property is preferred over the xml:space attribute.

3.13 Style Sheet Attribute Module

This module adds the style attribute to the Common attribute collection (section 3.1).

3.14 Link Module

Elements Attributes Supported
link Common, See Collection
charset (Charset), Yes
href (URI), Yes
hreflang (LanguageCode), No
media (MediaDesc), Yes
rel ("stylesheet"), Yes
rev (LinkTypes), No
type ("text/css")Yes

Table Note:

† See [XHTMLMOD],section 4.3

If the printer implements language selection then the hreflang attribute must be supported.

3.15 Base Module

Elements Attributes Supported
base href* (URI)Yes

Table Notes:

† See [XHTMLMOD],section 4.3

* The attribute must be present.

3.16 Character Entities

XHTML-Print is in the family of XHTML document types, since it is created by combining XHTML modules. The character entities that are part of XHTML-Print are, therefore, defined in XHTML Character Entities ([XHTMLMOD], Section F.1).

4. How to Use XHTML-Print

XHTML-Print inherits all the structure, encoding and other basic infrastructure specified by XHTML1.0 [XHTML1]. The following sections describe and clarify the application and usage restrictions of XHTML-Print.

4.1 Recommended Attributes on the "img" and "object" Elements

Because many printers create the page in a serial manner from top to bottom, it is important for the printer to know the size of images before retrieving the image data itself. This information is then used to create portions of the page layout.

Therefore, the sender should include the height and width attributes within the img or the object element. Printers may omit from the page images that do not include height and width attributes (see item 2, Images, of section 2.3.1 ). These attributes may be expressed as pixels or percentages within the img or the object element. Percentages are relative to the parent element and not the page width or printable area.

This document specifies only one mandatory image format: baseline JPEG as defined in [JPEG]. See Appendix A for a description of JPEG decoder requirements. Printers are not required to support:

within the JFIF and EXIF files.

4.2 Style Sheets

Conforming XHTML-Print printers shall support both in-line and referenced style sheets within the style element or link element in the head element of a document. Conforming XHTML-Print printers shall also support the style attribute (i.e. in-line style) when used within other elements as defined by XHTML 1.1[XHTML1.1]. Normal cascading rules apply.

4.3 Image Data

In traditional web-based applications of XHTML, image data is contained in a separate file on a web server that the user agent retrieves.

However, there are circumstances where it is desirable to include the image data along with the rest of the print data. Some low cost, resource constrained clients may want to include images in their print output but cannot afford to include a server. Some print applications may require that all the print data can be encapsulated in a single file for transportability, avoiding firewall issues, etc.

See Appendix B for discussion of the method that shall be used to collect both XHTML-Print and associated image data into a single file or data stream.

4.4 Side-by-Side Images

Low-cost printers today often have very little memory into which page data can be stored before being printed. As such, they may build and print the page in swaths on the fly from the top of the page to the bottom. To enable the use of XHTML-Print in these low cost printers, some restrictions on the order of images contained in the XHTML-Print data stream must be added.

  1. If two or more images will be even partially side-by-side on the printed page they should be included by reference ( <img src="http://10.10.10.2/images/logo.jpg"> or <object data="http://10.10.10.2/images/logo.jpg">) rather than included inline. (See Appendix B). This allows the printer to get chunks of the image, as it needs it, as it prints down the page.
  2. An XHTML-Print conforming printer lacking sufficient buffer space to hold multiple side-by-side images may choose to reformat the layout of the page to preserve content. Printers shall attempt to preserve content when encountering side-by-side images that may be impossible to print as specified within the XHTML-Print. Discarding the second and subsequent of the side-by-side images should be avoided unless preservation of content is best achieved by doing so. Other than attempting to best preserve content, this specification does not mandate any specific behavior when encountering this situation. Clients providing images inline should order them from left-to-right top-to-bottom unless the print direction is known to be otherwise.

4.5 Forms Usage

An HTML form is a dynamic entity when the document is displayed in a browser : data can be entered into text fields, buttons may be pushed, selections made, and options checked. None of this dynamic activity can be rendered on a printed page. However, a printed page can permanently record a particular state of the form. For example, users may wish to print forms that record products ordered or payments made.

The following discussion illustrates the activity involved when interacting with and printing forms. Please refer to Sequence Diagram 1

Sequence diagram of user, browser, and printer interactions
Sequence Diagram 1. Forms Usage

Steps:
  1. The user interacts with a browser on a mobile device to access a form presented by a server on the network (lines 1 and 2 of Sequence Diagram 1). The following fragment of an XHTML-Print document shows what the server sends to the browser to present to the user. Please note, that the form is blank when first presented to the user.

    <form action="http://example.com/prog/adduser" method="post">
    <label for="firstname">First name: </label>
    <input type="text" id="firstname" /><br />
    <label for="lastname">Last name: </label>
    <input type="text" id="lastname" /><br />
    <label for="email">email: </label>
    <input type="text" id="email" size="40" /><br />
    <input type="checkbox" name="member" value="IEEE" /> IEEE <br />
    <input type="checkbox" name="member" value="ACM" /> ACM <br />
    <input type="submit" value="Send" /> <input type="reset" />
    </form>

    Here is an example presentation of the above form as the user would see it:




    IEEE
    ACM

  2. The user enters data (line 3 of Sequence Diagram 1) into the text fields and checks the IEEE check box so that the form now looks like the following:



    IEEE
    ACM

  3. The user then clicks on the browser's print button (line 4 of Sequence Diagram 1), to print the form as it currently appears.
  4. The browser then creates a, possibly new, document (line 5 of Sequence Diagram 1) containing the original form and the users data. Note in the XHTML-Print document below, created by the browser, that the user's data is include either by a value attribute or a checked attribute.

    <form action="http://example.com/prog/adduser" method="post">
    <label for="firstname">First name: </label>
    <input type="text" id="firstname" value="John"/><br />
    <label for="lastname">Last name: </label>
    <input type="text" id="lastname" value="Doe"/><br />
    <label for="email">email: </label>
    <input type="text" id="email" value="johnd@example.org" /><br />
    <input type="checkbox" name="member" checked="checked" value="IEEE" /> IEEE <br />
    <input type="checkbox" name="member" value="ACM" /> ACM <br />
    <input type="submit" value="Send" /> <input type="reset" /><br />
    </form>

  5. The browser sends (line 6 of Sequence Diagram 1) the document created in line 5 to the printer.
  6. Sometime later the user clicks on the submit form button (line 7 of Sequence Diagram 1) and the browser submits the form (line 8 of Sequence Diagram 1) using the procedures given in [HTML4], Forms Submission.

5. Acknowledgements

This section is informative.

This specification was prepared by the PWG XHTML-Print Working Group.

Editors:
Don Wright, Lexmark International
Melinda Grant, HP
Peter Zehler, Xerox
Jun Fujisawa, Canon
Jim Bigelow, Hewlett-Packard Co.
Elliott Bradshaw, Oak Technology Imaging Group

Members:

• Peter Zehler, Xerox• Fumio Nagasaka, Epson• Geoff Soord, Software 2000
• Hitoshi Sekine, Ricoh• Jerry Thrasher, Lexmark• Atsushi Uchine, Epson
• Shunsaku Miyazawa, Epson• Cameron Brodeur, Ricoh• David Hall, HP
• Bob Taylor, HP• Junichi Ota. Ricoh• Rod Acosta, Agfa Monotype
• Lee Farrell, Canon• Alain Regnier, Ricoh• Yiruo Yang, Epson
• Athar Ahmad Minolta-QMS• Mabry Dozier, Minolta• Craig Whittle, Sharp
• Gail Songer, Peerless• Ted Tronson, Novell• Alan Berkema, HP
• Harry Lewis, IBM• Bill Wagner • Elliott Bradshaw, Oak Tech.

Special thanks to Allison Nuxoll of Hewlett-Packard for her helpful comments, and Elliott Bradshaw for his many reviews this document.

A. JPEG Decoder Requirements

A.1 Introduction

A.1.1 Intent

This appendix describes recommended behaviors for JPEG decoders in XHTML-Print devices. Behaviors for both minimal printers and enhanced layout printers are described. Many of the behaviors described in this document follow directly from language already present in the relevant JPEG standards, but are repeated here to emphasize their importance.

A.1.2 Objectives

The decoder behaviors described in this document are intended to minimize implementation complexity, while retaining maximum compatibility with existing JPEG files. In particular, these recommendations seek to ensure compatibility with both EXIF and baseline JFIF (i.e. the subset of JFIF files that use only baseline JPEG processes). Support for JPEG streams using non-baseline processes, such as arithmetic coding or progressive coding, is not mandated for XHTML-Print compliance.

A.2 Behaviors of Minimal Printers

This section describes behaviors of JPEG decoders for minimal XHTML-Print implementations.

A.2.1 JPEG Processes

A JPEG decoder for an XHTML-Print printer shall support all baseline JPEG processes as defined in [CCITT], except for 2- and 4-component images. These processes include grayscale and 3-component images, 8-bit/component sample depth, Huffman entropy coding, 444, 422, 411, and 400 subsampling modes, and sequential (i.e. non-progressive) scan.

A.2.2 Handling of APPx Markers

Baseline decoders may ignore application-specific markers, such as the JFIF APP0 marker and the EXIF APP1/APP2 markers. This will cause all images to print in an un-rotated orientation, with image size as specified in the JPEG SOF marker if not overridden by XHTML-Print mark-up. A JPEG decoder for a minimal printer shall not fail as a consequence of encountering an unsupported APPx marker (i.e. all such markers shall be correctly parsed, even if they are ignored).

A.2.3 Color Management

This section describes a recommended color management approach for minimal XHTML-Print printers.

Greyscale Images

Sample values in a grayscale (single-component) JPEG image shall be converted to the sRGB color space by setting

Rout= Gout = Bout = Grayin

Color Images

Sample values in 3-component JPEG images shall be interpreted as YCbCr samples, as would be obtained by applying the matrices described in ITU BT.601 [BT601.5] to sRGB input data.

A.3 JPEG Decoder for XHTML-Print Enhanced Layout Extension

This section describes behaviors of JPEG decoders for XHTML-Print devices that support the XHTML-Print Enhanced Layout Extension, an optional feature block. The behaviors described below should be interpreted as "in addition to" those described in XHTML-Print Document Type and Printer Conformance (the requirements for minimal XHTML-Print devices).

A.3.1 Handling of EXIF APP1 and APP2 Markers

A JPEG decoder for an XHTML-Print implementation which supports the Enhanced Layout Extension may decode the TIFF IFDs embedded in the EXIF APP1 and APP2 markers, as described in Section 2.6.4 of [JEIDA]. The following IFDs may be supported. However, any future XHTML elements or CSS properties affecting image orientation shall take precedence over these IFDs.

Tag Name Field Name Description
Orientation of Image Orientation Sets image orientation in 90-degree increments, and enables transposition.

B. Inline Image Data

B.1 Introduction

B.1.1 Intent

The intent of this appendix is to describe the method for including XHTML-Print and associated image data in a single data stream or file. Support for Inline Image Data is conditionally mandatory; i.e. any device supporting Inline Image Data shall support this method. (See Image Data.) Mandating support for Inline Image Data is outside the scope of this document.

In addition to images, if separate style sheets are to be interleaved with the XHTML-Print data, the same method shall be used.

B.1.2 Objectives

B.2 MIME type Application/Multiplexed

This section includes by reference the entirety of "The MIME Application/Multiplexed Content-type", Robert Herriot [MIMEMPX].  For all printers that support inline data, [MIMEMPX] shall be supported.

Producers and consumers of Application/Vnd.pwg-multiplexed entities, as defined in [MIMEMPX], should consider each component image message of the compound document as having one and only one reference. The producer of the compound document must assume that the consumer of the Application/Vnd.pwg-multiplexed entity has limited memory and therefore include a unique image message for each image reference found in the root document. If a ContentID is present in the header of an image message, that ContentID must be unique. If a Content-Location is present in the header of an image message, that Content-Location is required to be unique except for the special case where a repeated reference to the same image URL causes several messages containing the same image data to be present in the compound document. Consumers may release the message data associated with an image reference as the image is rendered, because the Consumer can be confident that another reference to the same image will be accompanied by another message containing the image data. Consumers may also substitute image data for a message with a given Content-Location header value with image data from other messages with the same Content-Location header value because Consumers can be confident that messages with identical Content-Location values do in fact contain identical data.

URL references in the the root document of the multiplexed document must be matched to Content-Location and/or Content-ID fields of the referenced message object according to the rules given by [RFC2557]. An exception to the rules given by [RFC2557] occurs when a reference is made to a message object named with a Content-Location. In that special case, multiple instances of that message are required in the compound document.

B.3 Using object for In-Line Image Data

This section is informative.

An alternative method to include inline image data in XHTML-Print is via the object element and a forward reference. The declare attribute of the object element is used to define the object, but delay its processing. The id attribute is used to associate the forward reference with the image content, sent at the end of the XHTML-Print document. Because this method normally encodes the binary image data using base64 encoding, a significant increase in the size of the data transmitted will be experienced. This should be avoided over low speed connections.  Printers supporting inline data may support base64 encoding using object.

See RFC2397 for information on the "data" URL scheme.


<object declare="declare"
   height="20 mm" width="20 mm"
   type="image/jpeg"
   id="image_1" >
</object>

. . . .

<object id="image_1"
   data="data:image/jpeg;base64,aGh67Fghsapa0Hji7dfGSweTa . . . ">
</object>

This method may be useful for very simple clients that cannot afford a server for image download or for some reason cannot utilize the Application/Multiplexed MIME type; however, it is not recommended for general use especially if the size of the printer's buffer is unknown.

C. XHTML-Print DTD and Modules

This appendix is normative.

This section contains the pieces of the XHTML-Print DTD that are unique to XHTML-Print. The remaining entities and modules are as specified in reference [XHTMLMOD].

The following should be used from Modularization of XHTML [XHTMLMOD]:

  1. xhtml-attribs-1.mod
  2. xhtml-base-1.mod
  3. xhtml-basic-form-1.mod
  4. xhtml-basic-table-1.mod
  5. xhtml-blkphras-1.mod
  6. xhtml-blkpres-1.mod
  7. xhtml-blkstruct-1.mod
  8. xhtml-charent-1.mod
  9. xhtml-datatypes-1.mod
  10. xhtml-framework-1.mod
  11. xhtml-hypertext-1.mod
  12. xhtml-image-1.mod
  13. xhtml-inlphras-1.mod
  14. xhtml-inlpres-1.mod
  15. xhtml-inlstruct-1.mod
  16. xhtml-inlstyle-1.mod
  17. xhtml-lat1.ent
  18. xhtml-link-1.mod
  19. xhtml-list-1.mod
  20. xhtml-meta-1.mod
  21. xhtml-notations-1.mod
  22. xhtml-object-1.mod
  23. xhtml-param-1.mod
  24. xhtml-pres-1.mod
  25. xhtml-qname-1.mod
  26. xhtml-special.ent
  27. xhtml-struct-1.mod
  28. xhtml-style-1.mod
  29. xhtml-symbol.ent
  30. xhtml-text-1.mod

C.1. XHTML-Print 1.0 DTD

<!-- ....................................................................... -->
<!-- XHTML-Print 1.0 DTD ................................................... -->
<!-- file: xhtml-print10.dtd
-->

<!-- XHTML-Print 1.0 DTD

     This is XHTML-Print 1.0, a variant of XHTML Basic for printing.

     Copyright 2001-2003 Printer Working Group, All Rights Reserved.
     

     Permission to use, copy, modify and distribute the XHTML-Print DTD and
     its accompanying documentation for any purpose and without fee is hereby
     granted in perpetuity, provided that the above copyright notice and
     this paragraph appear in all copies.  The copyright holders make no
     representation about the suitability of the DTD for any purpose.

     It is provided "as is" without expressed or implied warranty.

        Author:   Jun Fujisawa <fujisawa.jun@canon.co.jp>
        Revision: $Id: xhtml-print10.dtd,v 1.5 2003/02/09 06:59:04 fujisawa Exp $


-->
<!-- This is the driver file for version 1.0 of the XHTML-Print DTD.

     This DTD is identified by the PUBLIC and SYSTEM identifiers:

        PUBLIC "-//PWG//DTD XHTML-Print 1.0//EN"
        SYSTEM "http://www.xhtml-print.org/xhtml-print/xhtml-print10.dtd"
-->
<!ENTITY % XHTML.version "-//PWG//DTD XHTML-Print 1.0//EN" >

<!-- Use this URI to identify the default namespace:

         "http://www.w3.org/1999/xhtml"
-->
<!ENTITY % NS.prefixed "IGNORE" >
<!ENTITY % XHTML.prefix "" >

<!-- Reserved for use with the XLink namespace:
-->
<!ENTITY % XLINK.xmlns "" >
<!ENTITY % XLINK.xmlns.attrib "" >

<!-- reserved for future use with document profiles -->
<!ENTITY % XHTML.profile "" >

<!-- Bidirectional Text features
     This feature-test entity is used to declare elements
     and attributes used for bidirectional text support.
-->
<!ENTITY % XHTML.bidi "IGNORE" >

<!-- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -->

<!ENTITY % xhtml-events.module "IGNORE" >
<!ENTITY % xhtml-bdo.module "%XHTML.bidi;" >

<!-- Style Attribute Module ............................ -->
<!ENTITY % xhtml-inlstyle.module "INCLUDE" >
<![%xhtml-inlstyle.module;[
<!ENTITY % xhtml-inlstyle.mod
     PUBLIC "-//W3C//ENTITIES XHTML Inline Style 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-inlstyle-1.mod" >
%xhtml-inlstyle.mod;]]>

<!-- Document Model Module ............................. -->
<!ENTITY % xhtml-model.mod
     PUBLIC "-//PWG//ENTITIES XHTML-Print 1.0 Document Model 1.0//EN"
            "http://www.pwg.org/xhtml-print/xhtml-print10-model-1.mod" >

<!-- Modular Framework Module (required) ............... -->
<!ENTITY % xhtml-framework.mod
     PUBLIC "-//W3C//ENTITIES XHTML Modular Framework 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-framework-1.mod" >
%xhtml-framework.mod;

<!-- Text Module (required) ............................ -->
<!ENTITY % xhtml-text.mod
     PUBLIC "-//W3C//ELEMENTS XHTML Text 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-text-1.mod" >
%xhtml-text.mod;

<!-- Hypertext Module (required) ....................... -->
<!ENTITY % xhtml-hypertext.mod
     PUBLIC "-//W3C//ELEMENTS XHTML Hypertext 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-hypertext-1.mod" >
%xhtml-hypertext.mod;

<!-- Lists Module (required) ........................... -->
<!ENTITY % xhtml-list.mod
     PUBLIC "-//W3C//ELEMENTS XHTML Lists 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-list-1.mod" >
%xhtml-list.mod;

<!-- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -->

<!-- Presentation Module ............................... -->
<!ENTITY % xhtml-pres.module "INCLUDE" >
<![%xhtml-pres.module;[
<!ENTITY % xhtml-pres.mod
     PUBLIC "-//W3C//ELEMENTS XHTML Presentation 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-pres-1.mod" >
%xhtml-pres.mod;]]>

<!-- Image Module ...................................... -->
<!ENTITY % xhtml-image.module "INCLUDE" >
<![%xhtml-image.module;[
<!ENTITY % xhtml-image.mod
     PUBLIC "-//W3C//ELEMENTS XHTML Images 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-image-1.mod" >
%xhtml-image.mod;]]>

<!-- Tables Module ..................................... -->
<!ENTITY % xhtml-table.module "INCLUDE" >
<![%xhtml-table.module;[
<!ENTITY % xhtml-table.mod
     PUBLIC "-//W3C//ELEMENTS XHTML Basic Tables 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-basic-table-1.mod" >
%xhtml-table.mod;]]>

<!-- Forms Module ...................................... -->
<!ENTITY % xhtml-form.module "INCLUDE" >
<![%xhtml-form.module;[
<!ENTITY % xhtml-form.mod
     PUBLIC "-//W3C//ELEMENTS XHTML Basic Forms 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-basic-form-1.mod" >
%xhtml-form.mod;]]>

<!-- Style Sheet Module ................................ -->
<!ENTITY % xhtml-style.module "INCLUDE" >
<![%xhtml-style.module;[
<!ENTITY % xhtml-style.mod
     PUBLIC "-//W3C//ELEMENTS XHTML Style Sheets 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-style-1.mod" >
%xhtml-style.mod;]]>

<!-- Link Module ....................................... -->
<!ENTITY % xhtml-link.module "INCLUDE" >
<![%xhtml-link.module;[
<!ENTITY % xhtml-link.mod
     PUBLIC "-//W3C//ELEMENTS XHTML Link Element 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-link-1.mod" >
%xhtml-link.mod;]]>

<!-- Metainformation Module ............................ -->
<!ENTITY % xhtml-meta.module "INCLUDE" >
<![%xhtml-meta.module;[
<!ENTITY % xhtml-meta.mod
     PUBLIC "-//W3C//ELEMENTS XHTML Metainformation 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-meta-1.mod" >
%xhtml-meta.mod;]]>

<!-- Base Module ....................................... -->
<!ENTITY % xhtml-base.module "INCLUDE" >
<![%xhtml-base.module;[
<!ENTITY % xhtml-base.mod
     PUBLIC "-//W3C//ELEMENTS XHTML Base Element 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-base-1.mod" >
%xhtml-base.mod;]]>

<!-- Param Module ...................................... -->
<!ENTITY % xhtml-param.module "INCLUDE" >
<![%xhtml-param.module;[
<!ENTITY % xhtml-param.mod
     PUBLIC "-//W3C//ELEMENTS XHTML Param Element 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-param-1.mod" >
%xhtml-param.mod;]]>

<!-- Object Module ..................................... -->
<!ENTITY % xhtml-object.module "INCLUDE" >
<![%xhtml-object.module;[
<!ENTITY % xhtml-object.mod
     PUBLIC "-//W3C//ELEMENTS XHTML Embedded Object 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-object-1.mod" >
%xhtml-object.mod;]]>

<!-- Structure Module (required) ....................... -->
<!ENTITY % xhtml-struct.mod
     PUBLIC "-//W3C//ELEMENTS XHTML Document Structure 1.0//EN"
            "http://www.w3.org/TR/xhtml-modularization/DTD/xhtml-struct-1.mod" >
%xhtml-struct.mod;

<!-- end of XHTML-Print 1.0 DTD ............................................ -->
<!-- ....................................................................... -->


C.2. XHTML-Print 1.0 Document Model Module

<!-- ....................................................................... -->
<!-- XHTML-Print 1.0 Document Model Module ................................. -->
<!-- file: xhtml-print10-model-1.mod

     This is XHTML-Print 1.0, a variant of XHTML Basic for printing.

     Copyright 2001-2003 Printer Working Group, All Rights Reserved.
     Revision: $Id: xhtml-print10-model-1.mod,v 1.5 2003/02/09 06:59:04 fujisawa Exp $


     This DTD module is identified by the PUBLIC and SYSTEM identifiers:

        PUBLIC "-//PWG//ENTITIES XHTML-Print 1.0 Document Model 1.0//EN"
        SYSTEM "http://www.xhtml-print.org/xhtml-print/xhtml-print10-model-1.mod"

     ....................................................................... -->

<!-- XHTML-Print 1.0 Document Model

     This module describes the groupings of elements that make up
     common content models for XHTML-Print elements.
-->

<!-- Optional Elements in head ......................... -->

<!ENTITY % HeadOpts.mix
     "( %meta.qname; | %link.qname; | %object.qname; | %style.qname; )*" >

<!-- Miscellaneous Elements ............................ -->

<!ENTITY % Misc.class "" >

<!-- Inline Elements ................................... -->

<!ENTITY % InlStruct.class "%br.qname; | %span.qname;" >

<!ENTITY % InlPhras.class
     "| %em.qname; | %strong.qname; | %dfn.qname; | %code.qname;
      | %samp.qname; | %kbd.qname; | %var.qname; | %cite.qname;
      | %abbr.qname; | %acronym.qname; | %q.qname;" >

<!ENTITY % InlPres.class
     "| %tt.qname; | %i.qname; | %b.qname; | %big.qname;
      | %small.qname; | %sub.qname; | %sup.qname; " >

<!ENTITY % I18n.class "" >

<!ENTITY % Anchor.class "| %a.qname;" >

<!ENTITY % InlSpecial.class "| %img.qname; | %object.qname;" >

<!ENTITY % InlForm.class
     "| %input.qname; | %select.qname; | %textarea.qname;
      | %label.qname;"
>

<!ENTITY % Inline.extra "" >

<!ENTITY % Inline.class
     "%InlStruct.class;
      %InlPhras.class;
      %InlPres.class;
      %Anchor.class;
      %InlSpecial.class;
      %InlForm.class;
      %Inline.extra;"
>

<!ENTITY % InlNoAnchor.class
     "%InlStruct.class;
      %InlPhras.class;
      %InlPres.class;
      %InlSpecial.class;
      %InlForm.class;
      %Inline.extra;"
>

<!ENTITY % InlNoAnchor.mix
     "%InlNoAnchor.class;
      %Misc.class;"
>

<!ENTITY % Inline.mix
     "%Inline.class;
      %Misc.class;"
>

<!-- Block Elements .................................... -->

<!ENTITY % Heading.class
     "%h1.qname; | %h2.qname; | %h3.qname;
      | %h4.qname; | %h5.qname; | %h6.qname;"
>
<!ENTITY % List.class  "%ul.qname; | %ol.qname; | %dl.qname;" >

<!ENTITY % Table.class "| %table.qname;" >

<!ENTITY % Form.class  "| %form.qname;" >

<!ENTITY % BlkStruct.class "%p.qname; | %div.qname;" >

<!ENTITY % BlkPhras.class
     "| %pre.qname; | %blockquote.qname; | %address.qname;"
>

<!ENTITY % BlkPres.class "| %hr.qname;" >

<!ENTITY % BlkSpecial.class
     "%Table.class;
      %Form.class;"
>

<!ENTITY % Block.extra "" >

<!ENTITY % Block.class
     "%BlkStruct.class;
      %BlkPhras.class;
      %BlkPres.class;
      %BlkSpecial.class;
      %Block.extra;"
>

<!ENTITY % Block.mix
     "%Heading.class;
      | %List.class;
      | %Block.class;
      %Misc.class;"
>

<!-- All Content Elements .............................. -->

<!ENTITY % FlowNoTable.mix
     "%Heading.class;
      | %List.class;
      | %BlkStruct.class;
      %BlkPhras.class;
      %BlkPres.class;
      %Form.class;
      %Block.extra;
      | %Inline.class;
      %Misc.class;"
>

<!ENTITY % Flow.mix
     "%Heading.class;
      | %List.class;
      | %Block.class;
      | %Inline.class;
      %Misc.class;"
>

<!-- end of xhtml-print10-model-1.mod -->

D. References

D.1. Normative References

[HTML4]
"HTML 4.01 Specification", W3C Recommendation, D. Raggett, A. Le Hors, I. Jacobs, eds., 24 December 1999. Available at: http://www.w3.org/TR/1999/REC-html401-19991224.  The latest version is available at: http://www.w3.org/TR/html4
[XHTML1]
"XHTML 1.0: The Extensible HyperText Markup Language - A Reformulation of HTML 4 in XML 1.0", W3C Recommendation, Steven Pemberton, et al., 26 January 2000. Available at: http://www.w3.org/TR/2000/REC-xhtml1-20000126.  The latest version is available at: http://www.w3.org/TR/xhtml1
[XHTML1.1]
"XHTML 1.1 - Module-based XHTML", W3C Recommendation, Murray Altheim, Shane McCarron, eds., 31 May 2001. Available at: http://www.w3.org/TR/2001/REC-xhtml11-20010531.  The latest version is available at: http://www.w3.org/TR/xhtml11
[XHTMLBASIC]
"XHTML Basic", W3C Recommendation, Mark Baker, Masayasu Ishikawa, et al., eds., 19 December 2000 is available at: http://www.w3.org/TR/2000/REC-xhtml-basic-20001219.  The latest version is available at: http://www.w3.org/TR/xhtml-basic
[XHTMLMOD]
"Modularization of XHTML", W3C Recommendation, M. Altheim, F. Boumphrey, S. Dooley, S. McCarron, eds., 10 April 2001. Available at: http://www.w3.org/TR/2001/REC-xhtml-modularization-20010410.  The latest version is available at: http://www.w3.org/TR/xhtml-modularization
[XML]
"Extensible Markup Language (XML) 1.0 (Second Edition)", W3C Recommendation, T. Bray, J. Paoli, C. M. Sperberg-McQueen, E. Maler, eds., 6 October 2000. Available at: http://www.w3.org/TR/2000/REC-xml-20001006.  The latest version is available at: http://www.w3.org/TR/REC-xml
[CSSPP]
"CSS Print Profile", PWG Proposed StandardWorking Draft, D. Wright, J. Bigelow, eds. 31 March10 February 2003. Available at: http://www.pwg.org/xhtml-print/HTML-Version/CSS-Print.html
[CSS1]
"Cascading Style Sheets, level 1",W3C Recommendation,  Håkon Wium Lie, Bert Bos, eds., 11 January 1999. Available at: http://www.w3.org/TR/1999/REC-CSS1-19990111.  The latest version is available at: http://www.w3.org/TR/REC-CSS1
[CSS2]
"Cascading Style Sheets, level 2", W3C Recommendation, Bert Bos, Håkon Wium Lie, Chris Lilley, Ian Jacobs, eds., 12 May 1998.  Available at: http://www.w3.org/TR/1998/REC-CSS2-19980512 . The latest version is available at:  http://www.w3.org/TR/REC-CSS2/
[CSS3]
"Introduction to CSS3", W3C Working Group Draft, Eric A. Meyer, Bert Bos, eds., 23 May 2001.  Available at: http://www.w3.org/TR/2001/WD-css3-roadmap-20010523/. The latest version is available from: http://www.w3.org/Style/Group/css3-src/css3-roadmap/
[PAGEMEDIA]
"Paged Media Properties for CSS3", Working Group Draft, Robert Stevahn. Available from http://www.w3.org/TR/1999/WD-css3-page-19990928
[RFC2119]
"RFC2119 - Key words for use in RFCs to Indicate Requirement Levels", S. Bradner. It is available from http://www.ietf.org/rfc/rfc2119.txt?number=2119
[JPEG]
"JPEG File Interchange Format, version 1.02, September 1, 1992", C-Cube Microsystems. Available from ftp://ftp.uu.net/graphics/jpeg/jfif.ps.gz or ftp://ftp.uu.net/graphics/jpeg/jfif.txt.gz
[CCITT]
"CCITT Recommendation T.81 | ISO/IEC 10918-1, Digital Compression and Coding of Continuous-tone Still Images: Requirements and Guidelines", ISO. Available from http://www.iso.org/iso/en/StandardsQueryFormHandler.StandardsQueryFormHandler
[JEIDA]
"JEIDA-49-1998 Digital still camera image file format standard(exif)", Japan Electronics and Information Technology Industries Association (JEITA). Available from http://tsc.jeita.or.jp/
[MIMEMPX]
"RFC3391 - The MIME Application/Vnd.pwg-multiplexed Content-Type", R. Herriot. December 2002. It is available from http://www.ietf.org/rfc/rfc3391.txt
[RFC2397]
"RFC2397 - The "data" URL scheme", L. Masinter. It is available from http://www.ietf.org/rfc/rfc2397.txt
[RFC3023]
"RFC3023 - XML Media Types", M. Murata, S. St.Laurent, and D. Kohn. January 2001. It is available from http://www.ietf.org/rfc/rfc3023.txt.
[RFC3236]
"RFC3236 - The 'application/xhtml+xml' Media Type", M. Baker. January 2002. It is available from http://www.ietf.org/rfc/rfc3236.txt.
[RFC2557]
" RFC2557 - MIME Encapsulation of Aggregate Documents, such as HTML (MHTML)", J.Palme, A. Hopmann, N. Shelness, March 1999. It is available from http://www.ietf.org/rfc/rfc2557.txt.
[BT601.5]
ITU-R Recommendation BT.601-5, "Studio Encoding Parameters of Digital Television for Standard 4:3 and Wide-Screen 16:9 Aspect Ratios", October 1995. It is available from http://www.itu.int/ITU-R

D.2. Informative References

[RFC2045]
"RFC 2045 - Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", N. Freed, N. Borenstein, Section 6.8. "Base64 Content-Transfer-Encoding" is of particular interest. It is available at http://www.ietf.org/rfc/rfc2045.txt
[CHTML]
"Compact HTML for Small Information Appliances", W3C Note, T. Kamada, 9 February 1998. Available at: http://www.w3.org/TR/1998/NOTE-compactHTML-19980209
[GUIDELINES]
"HTML 4.0 Guidelines for Mobile Access, W3C Note, T. Kamada, T. Asada, M. Ishikawa, S. Matsui, eds., 15 March 1999. Available at: http://www.w3.org/TR/1999/NOTE-html40-mobile-19990315
The latest version is available at: http://www.w3.org/TR/NOTE-html40-mobile
[WCAG10]
"Web Content Accessibility Guidelines 1.0", W3C Recommendation, W. Chisholm, G. Vanderheiden, I. Jacobs, eds., 5 May 1999. Available at: http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505
The latest version is available at: http://www.w3.org/TR/WCAG10
[WML]
"Wireless Markup Language Specification", WAP Forum Ltd. Available from http://www.wapforum.org/what/technical.htm