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This document describes the use cases for a framework that combines documents by reference and the set of requirements for such a framework.
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
This is the first public Working Draft of the Compound Document by Reference Use Cases and Requirements document. It has been produced by the Compound Document Formats Working Group, which is part of the CDF Activity.
This is a Working Draft and is expected to change. The CDF Working Group does not expect this document to become a Recommendation. This document, after review and refinement, will be published and maintained as a Working Group Note.
In parallel, the CDF Working Group is producing a specification that combines document formats by reference, and meets the requirements listed here.
Comments and discussion on this document should be sent to public-cdf@w3.org (public archives).
Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
1 Introduction
1.1 Approach
1.1.1 Phases of Work
1.1.2 By Reference
1.1.3 By Inclusion
1.2 Definition of Rich Multimedia Content
1.3 Relationships With Other Technologies
1.3.1 HTML and XHTML
1.3.2 SVG
1.3.3 SMIL
1.3.4 XLink
1.3.5 XInclude
1.3.6 SOAP Attachments and Optimization Technologies
1.3.7 OASIS's Open Document Format
1.3.8 XForms
1.4 Definition of Terms
1.5 Who/what will implement the specification
1.5.1 Authoring tools and content production systems
1.5.2 Content players, such as browsers and plug-ins
1.5.3 Intermediary Processors, content renderers
2 Use Cases
2.1 Web Publishing and Broadcasting
2.1.1 Interactive News Service
2.1.2 Web Portal
2.1.3 News or stock ticker
2.1.4 Document viewing
2.1.5 Infotainment
2.2 Web Applications
2.2.1 Reservation system
2.2.2 Order entry system
2.2.3 On-line shopping
2.2.4 Survey
2.2.5 Games
2.2.6 Interactive maps
2.3 Resident Applications
2.3.1 Personal Information Management
2.3.2 Communication
2.3.3 Dynamic graphics as background or screen saver in mobile phone
2.3.4 Document viewing
2.3.5 Interactive Icon bar
2.3.6 Interactive Maps
2.4 Content Authoring, Aggregation and Deployment
2.4.1 Personal content creation
2.4.2 Personal content management
2.4.3 Web logs
2.4.4 Content aggregation
2.4.5 Professional content management
2.5 Navigation
2.5.1 SVG used as logo or advertisment (no links in SVG).
2.5.2 SVG embedded interactive map (links in SVG).
2.5.3 Menu with SVG images that animate and expand when focused (no links in SVG)
2.5.4 SVG image is embedded interactive part of the Web page (SVG has
links)
3 Requirements
3.1 High-Level Requirements
3.1.1 CDR MUST exploit existing specifications, favoring W3C
specifications wherever possible
3.1.2 CDR SHOULD NOT define new markup unless absolutely
required for integration purposes
3.1.3 CDR MUST provide the ability to define Rich Multimedia
Content
3.1.4 CDR MUST specify a base set of formats, corresponding
profiles and versions
3.1.5 Each CDR profile and version MUST specify, which formats can be referenced
3.1.6 CDR MUST specify, for each format, the element used to
reference other formats, if any.
3.1.7 CDR MAY specify generic integration techniques
3.1.8
CDR MUST support temporal synchronisation of dynamic content
coming from multiple references, possibly with multiple
references to the same source.
3.1.9 CDR MUST ensure that user agent controls work consistently
regardless of the component that has focus
3.1.10 CDR MUST support event mechanisms that cross namespace boundaries
3.1.11 CDR MUST support scriptability
3.1.12 CDR MUST say the allowed nesting level of referencing
3.1.13 CDR MUST explain how scripting interacts between components and the host document
3.1.14 CDR MUST explain which events get dispatched to the referenced document
3.1.15 CDR profiles MUST define how eventing (such as events, focus
or links) work across namespaces
3.1.16 CDR profiles MUST specify how event propagation works
across namespace boundaries.
3.1.17 CDR profiles MUST specify how focus traversal works with
referenced documents.
3.1.18 CDR profiles MUST specify how link activation work with
referenced document.
3.1.19 CDR profiles MUST specify triggering of animations across namespaces.
3.1.20 CDR MUST support fragment identifiers in cross-namespace
interaction
3.1.21 CDR MUST support a unified rendering model
3.1.22 CDR profiles SHOULD provide a method for adding event
handlers using declarative markup for the formats it uses
3.1.23 CDR documents MUST cater for accessibility requirements
3.1.24 CDR documents MUST support dynamic updating
3.1.25 CDR must define its integration into the Web
Architecture. It must include delivery over HTTP and should also
strive to be transport independent
3.1.26 CDR MUST allow compression of the data
3.1.27 CDR MUST allow packaging of the data
3.1.28 CDR MUST define the sharing of fonts among all components of a document
3.1.29 CDR MUST support server-side adaptation
3.1.30 CDR MUST support limited bandwidth networks and limited
capability devices
3.2 CDR Profile 1 Requirements (Rich Multimedia Content)
3.2.1 CDR Profile 1 MUST support user interaction model
3.2.2 CDR Profile 1 MUST explain how User Agent is able to identify a CDR Profile 1 document
3.2.3 CDR Profile 1 MUST support scalable graphics
3.2.4 CDR Profile 1 MUST support audio
3.2.5 CDR Profile 1 MUST support grid, flow, overlapping layouts
3.2.6 CDR Profile 1 MUST define transparency support for SVG backgrounds
3.2.7 CDR Profile 1 MAY define transparency support for XHTML backgrounds
3.2.8 CDR Profile 1 MUST support identification of markup and versions in CDF documents
3.2.9 CDR Profile 1 MUST support scalable diagrams that can be animated
and can cause link traversal
3.2.10 CDR Profile 1 MUST define how to reference SVGT graphics and resources
from an XHTML document
3.2.11 CDR Profile 1 MUST support advertising the specific supported versions
of formats and capabilities in headers
3.2.12 CDR Profile 1 MUST support XHTML as a root/host language
3.2.13 The XHTML <object> element MUST be used for referring to
other formats from XHTML
3.2.14 CDR Profile 1 MUST support Non-interactive Background SVG
3.2.15 CDR Profile 1 MUST define for animated SVG icons to act like HTML
images (no need for interactivity, links, zoom and pan)
3.2.16 CDR Profile 1 MUST define a way for events to trigger SVG
animation
3.2.17 CDR Profile 1 MUST define how an XHTML document can reference an SVG Tiny document
3.2.18 CDR Profile 1 MUST define the interaction model for an SVG
document referenced by an XHTML document
3.2.19 CDR Profile 1 MUST define the process for real-estate negotiation
between an XHTML document and a referenced SVG document
3.2.20 CDR Profile 1 MUST define handling of leftover SVG area
3.2.21 CDR Profile 1 MUST define system font support in SVG
A References (Non-Normative)
B Acknowledgements (Non-Normative)
C Changes Log (Non-Normative)
Compound Document Formats Working Group is producing recommendations on combining separate component technologies (e.g. XML-based languages, elements and attributes from separate namespaces), like XHTML, SVG, XForms, MathML, and SMIL, with a focus on user interface markups. This work is divided in phases and two technical solutions; compounding by reference and by inclusion.
The phases of work lists a set of languages (with their profiles) that are combined. As the languages differ by their features and properties, different issues come up when combining together different languages. Therefore, the phase constrains the issues that are currently solved.
The standardization starts with a limited set of languages. Once issues on these languages are solved, a next larger package is started. The following phases contain more languages and therefore, the corresponding recommendations solve wider variety of combining issues.
Each phase results in:
The first technical solution for compounding document formats is compounding by reference. This means that documents using different languages (namespaces) are linked by a reference such as XLink references, XHTML <img>, <object>, and <link> elements, and XForms model and instance src attributes. This allows separate languages to work together, but it allows implementations of the languages be separated.
The standardized issues are for example, how events flow in multi-document environment, how different documents are accessed by the scripts, and how different languages should cooperate in drawing to the screen.
A subsequent phase will address document combining by inclusion. The inclusion means that several languages (namespaces) are used within one document. There is no more need to put different languages (namespaces) in separate document but they can be used together.
The standardized issues here are for example, how different language implementations share the document, how non-orthogonal language features interact, and how different language implementations cooperate in more general way.
This specification addresses UI languages in order to facilitate rich multimedia content, which can include the following characteristics.
There are many technologies that allow combining different languages. Basically, all extensible languages provide this feature. The combining technologies and issues can be divided in two categories. The first category is how the compounding is described. The second category is how the semantics of compounding is understood. Each language specifies the first category. The compounding recommendations try to solve the second ones.
The following table shows existing W3C formats which are relevant to rich multimedia content. Each combination for which there is a requirement is annotated with comments. This is here to show the relationship between current W3C recommendations and the definition of rich multimedia content: 1.2 Definition of Rich Multimedia Content.
Use Case | XHTML + CSS | SVG | SMIL | XForms | VoiceXML | XBL | DOM/Scripting | |
Graphically rich content, possibly including animated background image. | Need CSS's 'background-*' properties | Need SVG's animated graphics [SVG.t 1.1 is sufficient] | . | . | . | . | . | |
Content author/provider has exact control of the presentation, including fonts, layout, colour, etc. | For when author/provider requires exact control in flowable scenarios | For when author/provider requires exact control in fixed canvas scenarios [SVG.t 1.1 is sufficient] | . | . | . | . | . | |
Layout adaptation: layout can be based upon device characteristics - screen size, colour depth, resolution, orientation. | For some scenarios, CSS box model layout and @media will be part of solution | For some scenarios, scalable graphics will be part of the solution [SVG.t 1.1 is sufficient] | For some scenarios, <smil:switch> facilities will be part of the solution [SMIL Basic???] | . | . | . | . | |
Navigation (forward/backwards tab, up/down/left/right, accesskey, pointer, voice), graphical menus, interactivity and animations. | Need XHTML <form> elements to define navigation points | For graphical menus, rich interactivity and animations [SVG.t 1.2 required for scripting and navigation] | . | For device-independent representation of human-computer interaction | For voice | . | Until richer declarative programming facilities are invented, any interesting interactivity requires scripting | |
Menuing system e.g., items get animated when focused. | For some scenarios, XHTML+CSS is sufficient for menus | For rich UI and animation [SVG.t 1.2 for scripting] | . | . | . | . | Generally you need script to respond to menu actions | |
Portable user interface. | For some scenarios, XHTML+CSS is sufficient for portable UIs | For some scenarios, XHTML+CSS is sufficient for portable UIs [SVG.t 1.2 required for scripting] | . | For device-independent representation of human-computer interaction | For voice | . | . | |
Presentation can be customized to reflect brand or user's personality. | For some scenarios, XHTML+bitmaps is sufficient | For some scenarios, SVG's richness is a requirement [SVG.t 1.1 is sufficient] | . | . | . | . | . | . |
Skinnable user interface e.g., ability to skin a document with animations and interactivity. | . | For rich graphics, animations and rich interactivity [SVG Full 1.2 for sXBL, otherwise SVG.t 1.2] | . | XForms provides the definition of the abstract UI components before skinning is applied | If you want to skin for voice | This is the design center for XBL | . |
HTML has an <object> element. This element can be used to compound by reference. The <object> element provides a way to link to external languages.
SVG has a <foreignObject> element. This element can be used to compound by reference. The <foreignObject> element provides a way to link to external languages.
SMIL technologies are closely related to compounding by reference. The SMIL provides a way to compound separate languages together and to synchronize them with time.
Xlink specifies a generic reusable vocabulary for links in XML documents. An XLink may be specified on an arbitrary element in an arbitrary namespace in such a way that an XLink enabled processor will be able to understand the linking semantics of said element. A variety of linking behaviours (embedding, hyperlinking, etc.) may furthermore be described using additional linking metadata.
XInclude specifies how to combine different infosets together. This approach may be used for compounding by inclusion.
After the XInclude is processed, the WG's produced recommendations specify the semantics on how the application should understand the compound document.
SOAP Attachments provide a way to divide documents to several pieces for more efficient serialization and then combine them back. For the WG's produced recommendations, the SOAP Attachments are like XInclude technology. The compounding technology operates and provides semantic information on top of these serialization issues.
The OASIS effort is targeted at office productivity application, such as word processors, spreadsheets or presentation authoring tools. The work is focused on representing the full information contained in documents that are created and edited with such tools in an interoperable manner. On the other hand, the CDF effort is focused on combining formats for web publication and has a lot of focus on user agent environment, and runtime behavior. For example, the CDF efforts will focus on issues such as the runtime interaction model for documents including components from different XML formats. This is not addressed by the Open Document Format specification. The Open Document Format, on the other hand, specifies an office application compatible style model, page layouts, index generations, text fields, table formulas which the CDF specification does not address.
Compound documents can be authored by a variety of means including:
It is expected that there will be multiple categories of CDF authoring tools. Here are some examples:
Depending on the system, CDF content will be viewed in a variety of ways:
Systems that process, combine, re-order, re-format or otherwise render content based on context. An example is a content rendering engine which takes content in a device neutral form and renders it appropriately according to particular device or bearer characteristics (such as screen size or bandwidth).
The W3C and other bodies have created multiple XML syntaxes for various purposes, such as XHTML for on-line document viewing, SVG for 2D vector graphics or SMIL for multi-media synchronization. While there has been a lot of interest for these individual solutions, there has been a growing demand for a solution that would let end-users use them together to define a single content. The individual markups as the one just mentioned have great features, but these features become even more compelling when combined. For example, being able to display scalable 2D images in XHTML pages provides the ability to define pages which can be printed with high quality. Similarly, using SVG images in an XHTML table provides an easy way to layout SVG images in a table.
There is a demand for letting content creators combine markups so as to create richer documents, containing multi-media information: text, graphics, audio and video. For that reason, the main use case for the CDF activity is the definition of rich multimedia content, as defined in 1.2 Definition of Rich Multimedia Content.
Services that mix text, audio, video and interactive elements to deliver information.
An interactive news service may provide the user with multimedia news content comprising traditional text and images, but also audio and video reports as well as diagrams which react to user behavior.
Note:
Example: newspaper Web sites that offer interactive features which go beyond textual content offered in a print edition.A "portal" application combines content and services from multiple back-end sources across multiple integration paths to create a cohesive user experience. Portals often are customizable to user preferences and other factors and therefore often produce dynamic content that is specific to a particular user-request.
An animated "ticker" which displays dynamic data, such as stock prices or current news headlines, can be displayed as part of a larger page of more static information, such as a news article.
The capability to view documents with preserved formatting, layout, images and graphics and interactive features such as zooming in and out and multi-page handling.
So-called infotainment services combine information and entertainment from different sources into a single interactive service with compelling presentation. The user experience for such services is often a single "page" which displays multiple pieces of content, each potentially of a different kind. These services often require dynamic user interfaces that use animation and other graphic effects to produce a pleasing user interface.
Note:
Example: mobile portals deployed by mobile network operators.Web applications typically have some form of programmatic control, either on the client, on the server or a combination of both. This document addresses client-side Web applications only. They may run within the user agent, or within another host application. A Web application is typically downloaded on demand each time it is "executed", allowing a developer to update the application for all users when needed. Web applications are usually smaller than regular desktop applications, and can have rich graphical interactive interfaces.
Interactive services which allow a user to book travel or make other kinds of reservations by using graphically-rich user interface. For instance, a user may use a calendar to pick a departure or check-in date and a map to locate a destination, with results represented as textual data for confirmation.
Note:
Example: online travel sites or airline sites.An application which might be used in the field to process orders for goods or services.
Note:
Examples: Parcel tracking application used by delivery agents; order entry system used by a mobile sales force.E-Commerce services which use interactive elements to display goods and enable a shopping experience.
A survey application which provides a multi-part form which can be stepped forward or backward and submitted in one action.
Interactive games that use animated content embedded within a page and using elements within the page to actuate functions within the game. For example, a simple painting game where the painting occurs in the animated area but a palate of colors are set outside of this area in the non-animated area.
These are applications which are resident or partially resident on a device.
In a mobile phone, a Web application is set as background or screen saver, and is dynamically updated depending on, for example, data from the network or the time of day. This allows the user to have immediate access to 'glancable' information, such as current weather conditions, stock quotes, or more application-oriented information such as flight departure data.
The capability to view documents with preserved formatting, layout, images and graphics and interactive features such as zooming in and out and multi-page handling.
This class includes tools and applications for both personal and professional content creation, management, and distribution.
Personal content is created by users themselves and, often, shared with other users. In many cases, users want to combine different content formats. A typical example is that use take a picture with mobile phone, write short message about the excellent meal that you had in the restaurant, and attach a map which shows the location of the restaurant.
Personal content management refers to storing your personal media content including images, audio, video, graphics, text, etc. It should be possible to link different content items to each other, view them simultaneously. In addition, the content management system should support adaptation of the content for different kinds of devices and sharing the content online with other users.
Blogs are personal diaries that are published online. Many bloggers try to create visually attractive content by combining different content formats.
In content aggregation, content coming from different sources is combined together. Web portals are typical examples. Often, content aggregators have different versions of the content offering for different delivery channels and user groups. Therefore, content filtering and transforming is often required. In addition, the content aggregators want to maintain certain look and feel of service across different devices and versions. Also, there might be need for Digital Rights Management (DRM).
SVG images are used as embedded logons or advertisments (with animations) in an XHTML document. There are no links in the SVG images. The user cannot focus the images, they are like bitmaps embedded by <img>.
An SVG image, which is an interactive city map, is embedded inside an XHTML page. There are links inside the SVG image. The user can navigate to the SVG map, which then gets focus. When the map has focus the user can either navigate further into the first link inside the map or skip the map and navigate further to the next link in the XHTML document.
SVG images are used as menu icons, wrapped inside <a> elements, in an XHTML document. There are no links inside the SVG images. When the user focuses a menu item, the icon expands and starts to animate. When the user moves to the next item, the animating icon returns to the state it had before it had focus, and the next icon, which now gets focus and starts to animate.
An SVG image is used as 2D-graphics in a Web page. The SVG image has links. The user can navigate directly from an XHTML link into the first link in the SVG image; the SVG image is seamlessly integrated with the XHTML page. The user navigates directly from the last link inside the SVG image to the next link, after the SVG image, in XHTML.
This is an alternative scenario in 2.5.2 SVG embedded interactive map (links in SVG). .
All the requirements collected by this WG are listed in the following sections.
These are general requirements for the Compound Documents by Reference (CDR) specification.
It is not the role of the Working Group to invent new markup, but rather to specify rules by which existing markup formats are combined.
It is not the role of the Working Group to invent new markup, but rather to specify rules by which existing markup formats are combined.
Rich Multimedia Content is defined in 1.2 Definition of Rich Multimedia Content.
Comformant implementations MUST support this base set.
Each CDR profile has a root document and one or more child documents. The CDR profile has to specify both the root document and the possible child documents.
For example, the CDR specification will specify that the XHTML <object> element is to be used for formats included in XHTML, and will specify the usage of this element to include other formats.
These are techniques that will be applicable beyond the set of formats, versions and profiles required by the CDR spec.
Support the synchronisation of multiple instances of dynamic content, such as animations, audio and video, within a single compound document.
Support every namespace in the compound document as a first class component.
Define consistent rules that specify how events pass to components. In particular, provide rules that define the behaviour when events are passed across namespace boundaries.
CDR have to support scripting languages. The scripts have to be able to access and modify the elements of both root and child documents.
Each CDR profile must define, whether there are restrictions to number of nesting levels. For example, whether a referenced SVG can itself reference another XHTML content.
CDF profile documents must explain what kind of access, if any, scripts have between the parent and child documents and vice-versa. Can a script in a child document access its parent's DOM, and if so, how? Can a script in a parent document access a child's DOM? If there is access, the mechanism must be described.
CDF profile documents must explain how, if at all, events get propagated from parent to child documents and vice-versa. Do events from a parent document get propagated to the children documents? Do events from a child document get propagated to the parent document?
With CDR profiles, documents in different namespaces can reference each other. The CDR profiles MUST specify multiple issues related to event propagation and handling.
For example, if an XHTML document references an SVG document, what is the event propagation model when the user activates an SVG element? Do events bubble from a child document to the referencing parent document? Does event capture happen from the root of the referenced document or does it happen from the root of the referencing document? This event propagation model MUST be consistent with the DOM Level 3 event model.
For example, when an XHTML document references an SVG document, what is the relation between the XHTML document's focus traversal and the SVG document's focus traversal. How does the SVG document get focus and how does the focus traversal starts in the SVG document? How does it end?
For example, if an XHTML anchor contains an reference to an SVG document which, itself, contains anchors, CDR profiles must specify which anchor takes precedence when the SVG document is moused-over (assuming a pointer interaction) or equivalently activated.
For example, if an XHTML document references an SVG document, the profile MUST specify how an SVG animation can be triggered by an XHTML event target.
In CDR, child documents within a parent document are referenced with URI references. This URI reference must support also so-called fragment identifiers. Each fragment identifier is passed to the component or plug-in that displays the child document, when the documents are loaded. The handling of the fragment identifiers depends on the MIME type of the child document.
Ensure that rendering is consistent across all components of a compound document. In particular, ensure that there are suitable rules that define how z-ordering applies between different components which may overlay one another. Also ensure that there are rules that define how transparency is handled when components overlay one another. CSS z-ordering may provide a mechanism for controlling this.
Event handlers contain instructions on how to react to certain event. These can be written either using a scripting language or a declarative (i.e., markup) language. The CDR specification should provide a method to add event handlers both to parent and child documents. If a CDR profile contains a markup language that supports declarative event handlers then the CDR profile should also support event handlers defined using markup.
All CDR profiles must take accessibility requirements in consideration. The Web Accessibility Initiative has defined Web Accessibility Guidelines, which must be used when CDR profiles are developed. In addition, markup language specific accessibility guidelines have been defined in Techniques for Web Content Accessibility Guidelines document. A CDR profile must support all the techniques that are supported by the markup language modules included in it. The same applies for the authoring tool accessibility guidelines and the user agent accessibility guidelines.
Dynamic documents can be manipulated by scripts, etc. The user interaction can fire events, which are caught by event handlers. The event handlers can then manipulate the elements via the DOM interface. These changes are then displayed to the user. CDR documents must support dynamic updating across different parent and child documents.
CDR profile documents must describe how they integrate into the Web Architecture, particularly in the areas of media types and transfer/transport protocols. It must be described how this works with HTTP as well as other protocols typically used to transfer Web content (e.g., RTP).
For efficiency, user agents and other renderers must support served content that is compressed in whole or part.
Packaging is needed in order to support optimization of the number of individual fetch operations that are required to construct the final user experience on the device (this is about multipart/mixed).
Every platform and device user agent, browser, or renderer behaves differently with respect to client provided fonts. Some have bitmap fonts and others have font engines that can produce vector fonts. Some provide access to these fonts, and others do not.
User agents, browsers and renderers must provide the possibility to use system fonts by components within documents if available and accessible. Since a resident system font cannot always be guaranteed, user agents must include a default font for use by components within the document when a font is required.
Some animations could be too heavy for some terminals - or could be too 'unsophisticated' for others.
Server side adaptation must therefore be possible in order to support less capable devices. In particular provide a means by which the SVG capabilities of the device can be communicated to the server. (for instance the rendering and animation capabilities in form of an index).
Small footprint and mobile devices often are connected to mobile networks, characterized by comparatively low bandwidth and/or high connection latency. Additionally, mobile networks may charge users for data downloaded. It is therefore desirable to ensure that this bandwidth is used optimally.
Authoring tools and/or systems serving CDR documents must be able to use techniques to reduce size of materials transmitted and the latency involved.
The language profile combining XHTML and SVG according to the CDR rules is referred to in this document as CDR Profile 1. This section identifies the requirements specific for the use of XHTML as the parent CDR Profile 1 document and SVG Tiny as the child document. This profile supports presentation of rich multimedia content, as defined in 1.2 Definition of Rich Multimedia Content, and many of the requirements herein are related to this definition. XHTML and SVG have been chosen as the first profile for CDR according to analysis of existing specifications and their applicability to rich multimedia content: 1.3 Relationships With Other Technologies
These requirements should be considered as additional requirements to the applicable requirements specified in other sections of the document.
CDR Profile 1 must support a clear user interaction model between components (event/focus management). Interactivity between components will help to provide a seamless and compelling user experience of documents which combine XHTML and media elements.
CDR Profile 1 content (that is, content which confirms to a language profile built using the CDR Profile 1 specification) will be unambiguously identified as conforming to that language profile.
Content creators and viewer implementations will both better be able to meet the conformance requirements of the CDR specifications if such content can be unambiguously identified. Use of a specific mime type will furthermore (through the use of accept headers) allow servers to perform a simple check on whether a suitable client is available.
Scalable graphics are required in order to easily deploy the same user interface onto multiple devices with different screen sizes / shapes and resolutions.
User agents must support the ability to play audio while rendering content. For example, a rendered document may choose to music play while the document is displayed.
In order to create rich content document, content authors need to ability to position and layout information items or user interface components. This is crucial authoring feature which also allows content to adapt to different screen sizes and aspect ratio. Layout is a complement to the scalable nature to formats such as SVG. In CDR Profile 1, grid and flow layouts MUST be supported. Overlapping layout, i.e., the ability to layout component that overlap completely or partially, MUST also be supported.
A CDR user agent MUST support static SVG background images and MAY support animated or scripted SVG background images. Authors however should not assume that the latter functionality will be available.
XHTML background images may be supported.
CDR Profile 1 must provide a mechanism for uniquely identifying the markups and versions used in a particular CDF documents. Ensure that this information can be used in content negotiation.
An example of usage is the implementation of buttons which render their own visual feedback (animated buttons for navigation). These will provide a scalable alternative to the use of images as the source of links that can be traversed. These should be allowed to contain animation, but not rich interaction.
A compound document by reference is defined as one root or parent document that makes a reference to another separate child document(s). Compound Document profiles that include SVG Tiny as referenced documents from XHTML must define how to reference the separate SVG Tiny graphics and resources.
When a user agent makes a request for content, it must identify the content types it can support. This is done by specifying the mime-type, version, and profile information, for each supported type of content, in the request. Using HTTP, this can be done by either using the HTTP ACCEPTS header or the UAProf.
However it is not necessarily the only root hosting language.
It is desirable to achieve the goal of embedding media and other objects into XHTML documents by using the existing <object> element rather than extending XHTML. The XHTML <object> element will be the method by which xml document types will be referenced from XHTML documents.
This allows for scalable (one size fits all) background images.
Zooming into a scalable image makes sense only if it was enlarged to the full screen-view before. Enable SVG to be used as an alternative to images. Icon mode so not interactive. Gives animation. Gives scalability. Icon mode includes any fixed diagram - no animation, but can be the subject of a link. (zoom and pan is not required for icon-mode SVG's, but for full view SVG's.)
This is required in order to support pleasing button animation on select and activate events, such as focus events, beyond the current "on/off" capability in CSS
CDR Profile 1 must specify how an XHTML document can refer to an SVG Tiny document such that the SVG Tiny document is rendered as a child document of the parent XHTML document.
To ensure interoperability, it is important that the CDR Profile 1 specification defines the interaction model for SVG documents referenced by XHTML documents. For example, the interaction model must define if and how interaction with an SVG document requires activation, or if activation is optional, how activation is controlled. By the same token, the interaction model should define the precedence rules between the SVG content and the referencing XHTML document, for example regarding hyperlinking: if an XHTML <object> is enclosed in an <a> element and the <object> references an SVG document which itself displays anchors, what is the behavior when clicking over one of the anchors in the SVG element?
CDR Profile 1 will provide comprehensive, mandatory rules that specify how document components from different namespaces are scaled when they occur within other components (right-sizing). Support the ability for relative size measures to be used by authors. Ensure that rules define the behaviour when fixed and relative sized components are used together within a single document. Ensure that the rules define the behaviour associated with areas of the containing component not filled by the contained component. Thus, it will be possible to create truly screen size-independent content.
Rendering SVG in a destination box that is fixed will usually end up in areas outside the SVG viewbox to become visible. These areas may be filled by the SVG (child) object.
SVGT does not mandate system fonts, but in the context of a user agent, highly optimized system fonts are available. On many devices (when executed in the context of a user agent), highly optimized fonts are available.
It is therefore necessary to make highly optimized terminal fonts (used by the user agent) available to SVG as system fonts and to support the ability for common font sets to be used throughout the combined document. In particular, platform fonts should be able to be used if supported, with support font fall-back mechanisms to provide defaults in the event that chosen fonts are unavailable. The SVG <text> element should always display something as long as it is within the viewport.
Related to CDR requirement: 3.1.28 CDR MUST define the sharing of fonts among all components of a document.
The editors would like to thank the contributers:
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