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1. Personal Needs and Preferences Properties

User preferences are defined to support web authors in delivering a best-fit match from resources available to a person's needs expressed in terms of modalities the user can receive. Not all content can readily meet a user's needs in every context but where preferences are available a better match might be made than where they are not. Matching a user's explicitly-expressed needs might require changing configurations on a delivery device, reporting to a web app what those preferences are and adaptations the device has made  to them and the web app may itself change configuration and may fetch and deliver alternative content to meet the needs.

In some cases a preference might be addressed directly and completely by a device. In some cases a device may partially address a preference and further support for that preference will need to be provided by a web app and in some cases the web app will address the preference.  This is likely to be different for each preference, device, environmental and other context.

1.1 Processing of Preferences

In this section we present an example as an introduction, ahead of its full definition.

This specification provides a number of Preference Property Definitions expressed in terms of sensory modalities and recognised adaptation types.  Each preference property instance consists of a (space-separated unordered) list of tokens taken from a strict vocabulary for that property.  For example the preference 

textualForAuditory

indicates a user wishes auditory resources to be replaced by or augmented by textual resources.  This may be done in different ways depending on the media context.  Its values are a list drawn from the vocabulary:

(true false captions transcript transcript-simultaneous)

Token Values
Description
true A preference that audio modalities are replaced or augmented by textual ones
false Default value - no preference
captions A preference that captions be delivered simultaneously with the audio
transcript A preference that video be replaced by a transcript.
transcript-simultaneous A preference that a transcript be delivered at the same time as audio or video

If the property has a value of '(true)' this is to be interpreted as a general requirement and a textual form delivered that is appropriate for the media concerned drawn from other tokens in that vocabulary as appropriate to the media context.  A value of (captions)  or (true captions) is to be interpreted as that the user wishes for audio to be accompanied by captions. It implies that the property is true and an intelligent system might infer that if captions are not available but a transcript is then this might be useful to deliver instead even though the user has not requested it explicitly.  The token 'false' must occur alone so a list of tokens containing 'false" and any other value is undefined (this includes '(true false)'.  The application should provide the best match to the user's preferences.

1.2 Organisation of Preference Properties

Properties are described in terms of the modalities to which they relate. There are two kinds:

An instance of a property consists of a (space separated, unordered) list of tokens drawn from a vocabulary for that property.

Where a property preference is for one modality over another delivery may be augmenting the one modality with another or replacing it depending on the best match to the user's context, which may be determinable from other preference settings. For example a user may specify that they prefer auditory information be delivered in textual form with the setting

textualForAuditory : true
A textual alternative might be delivered to the user instead of the audio or displayed simultaneously with rendering the audio. Note that some users find considerable benefit from simultaneous rendering of resources in multiple modalities, particularly but not exclusively users with particular cognitive disabilities, non-native language speakers and language learners.  The choice of whether to render the text simultaneously with the audio might be made by matching also to a user's language preferences or by the context of the media possibilities.

Each property instance has a value that consists of a list of tokens as specified in the definition of properties. Each token has an optional list of refinement parameters where such is meaningful.

1.2.1 Interpretation of values

[Editors note: This needs a little careful work to tighten it - for example for some vocabulary (true false X Y) is the instance (true) equivalent to (X Y) ? ]

Lists of values may not be logically inconsistent. In particular the following are prohibited and if they occur are undefined:
Where a list of values contains true and any other values the other values should be considered as refining the value true (i.e. providing more detail of what is preferred). A system responding to the value for some property of

(true)
might make intelligent inferences about media that might be useable by that user in that context.  Where a vocabulary contains terms (true, false, X, Y) and an instance of a property is either (true, X) or just (X) a system would ideally deliver an X if it is available but if an X is not available then the system might infer that a Y would be useful and deliver that instead.

1.3 Preference Property Definitions

1.3.1 auditory

Indicates a preference for auditory resources
Token Values
Description
true
Prefer auditory resources
false
Default value - no preference

Examples:


1.3.2 textual

Indicates a preference for textual resources
Token Values
Description
true
Prefer textual resources
false
Default value - no preference
Examples:

1.3.3 visual

Indicates a preference for visual resources
Token Values
Description
true
Prefer visual resources
false
Default value - no preference
highContrast Where visual is the preferred modality the preference is for presentation of text and images of text that has a contrast ratio of at least 4.5:1, or, for larger text, a contrast ratio of at least 3:1 (WCAG2 Checkpoint 1.4.3):
http://www.w3.org/TR/WCAG20/#visual-audio-contrast.
blackOnWhite black text and borders on a white background
whiteOnBlack white text and borders on a black background
inverseVideo Text, image and video colors reversed
Examples:

1.3.4 tactile

Indicates a preference for tactile resources
Token Values
Description
true
Prefer tactile resources
false
Default value - no preference
Examples:

1.3.5 textualForAuditory

Indicates a preference that an auditory resource or presentation be augmented by or replaced by a textual one


Token Values Description
true A preference that audio modalities are replaced or augmented by textual ones
false Default value - no preference
captions A preference that captions be delivered simultaneously with the audio
transcript A preference that video be replaced by a transcript.
transcript-simultaneous A preference that a transcript be delivered at the same time as audio or video
Examples:


1.3.6 textualForVisual

Indicates a preference that a visual resource or presentation be augmented by or replaced by a textual one

Token Values Description
true A preference that visual modalities are replaced or augmented by textual ones
false Default value - no preference
alternativeText A preference for alternative text instead of or together with a resource wth visual modality (typically an image)
longDescription A preference that a visual modality resource be replaced by or augmented by a longDesc.
Examples:

1.3.7 textualForTactile

Indicates a preference that a tactile resource or presentation be augmented by or replaced by a textual one

Token Values Description
true A preference that tactile modalities are replaced or augmented by textual ones
false Default value - no preference
Examples:

1.3.8 visualForAuditory

Indicates a preference that an auditory resource or presentation be augmented by or replaced by a visual one

Token Values Description
true A preference that auditory modalities are replaced or augmented by visual ones
false Default value - no preference
signLanguage A preference that an auditory resource be replaced by or augmented by a sign language presentation, as defined above [TBD url to defin]
Examples:

1.3.9 visualForTactile

Indicates a preference that a tactile resource or presentation be augmented by or replaced by a visual one

Token Values Description
true A preference that tactile modalities are replaced or augmented by visual ones
false Default value - no preference
Examples:

1.3.10 visualForTextual

Indicates a preference that a textual resource or presentation be augmented by or replaced by a visual one

Token Values Description
true A preference that textual modalities are replaced or augmented by visual ones
false Default value - no preference
Examples:


1.3.11 auditoryForVisual

Indicates a preference that an visual resource or presentation be augmented by or replaced by an auditory one

Token Values Description
true A preference that visual modalities are replaced or augmented by auditory ones
false Default value - no preference
audioDescription A preference that a visual resource (typically the visual component of a video) be replaced by or augmented by an audio description. Note that in some countries this is referred to as 'videoDescription'.
Examples:

1.3.12 auditoryForTactile

Indicates a preference that a tactile resource or presentation be augmented by or replaced by an auditory one

Token Values Description
true A preference that tactile modalities are replaced or augmented by auditory ones
false Default value - no preference
Examples:

1.3.13 auditoryForTextual

Indicates a preference that a textual resource or presentation be augmented by or replaced by an auditory one

Token Values Description
true A preference that textual modalities are replaced or augmented by auditory ones
false Default value - no preference
Examples:

1.3.14 tactileForAuditory

Indicates a preference that an auditory resource or presentation be augmented by or replaced by an tactile one

Token Values Description
true A preference that auditory modalities are replaced or augmented by tactile ones
false Default value - no preference
Examples:

1.3.15 tactileForVisual

Indicates a preference that a visual resource or presentation be augmented by or replaced by a tactile one

Token Values Description
true A preference that visual modalities are replaced or augmented by tactile ones
false Default value - no preference
Examples:

1.3.16 tactileForTextual

Indicates a preference that a textual resource or presentation be augmented by or replaced by a tactile one

Token Values Description
true A preference that textual modalities are replaced or augmented by tactile ones
false Default value - no preference
Examples:

1.3.17 languageOfAdaptation

Indicates a preference for adaptations to be delivered in a particular language. Note that this may not be the same language in which the user operates the device.
Token Values Description
Internal Language Code presented to user as string or selectable widget TBD: get IETF reference
undefined Preference is for adaptations to be delivered in the default user language for that device
Examples:

1.3.18 hazard

Indicates characteristics of resources that a user DOES NOT wish to receive because of potential hazards for that user. Note also that the meaning of a value of true without any other value is undefined for this property (i.e. it must have a refinement to be meaningful)
Token Values Description
false Default value - no preference
flashing A preference that a resource having a visual pattern that flashes more than three times in any one second not be delivered to the user. Note that this level of flashing can cause seizures in some users (WCAG2 Guideline 2.3.1 A):
http://www.w3.org/TR/WCAG20/#seizure].
flashingStrict A preference that a resource having a visual pattern that flashes more than three times in any one second not be delivered to the user. Note that this level of flashing can cause seizures in some users (WCAG2 Guideline 2.3.1 AAA):
 http://www.w3.org/TR/WCAG20/#seizure
motionSimulation A preference that a resource simulating motion not be delivered to the user. Note that for some users such a resource may induce nausea
sound  Prefer that resources generating an audio pattern that can cause the user to have seizures [ISO 29138] not be delivered to the user.
Examples:

1.3.19 ATInteroperable

Indicates that where possible resources that are interoperable with AT should be selected. Note that the default for this preference unless otherwise defined is true.
Token Values Description
true (default)
Resources that are interoperable with AT should be selected whenever possible. Interoperability is indicated by compliance with WCAG 2.0 checkpoints: 1.1.1, 1.3.1, 1.3.2, 2.4.4, 3.1.1, 3.1.2, 3.3.2, 4.1.1 and 4.1.2.
false explicit preference excluding this requirement
Examples:

1.3.20 simplePresentation

Indicates a preference for very simple presentation of interface and content even if the device supports more complex presentation (for example if the device large or high-resolution screen)

Token Values Description
true A preference for presentation to be of a similar level of complexity to that commonly delivered to small screen devices using agile design - typically no more than six controls or regions of interest on a page.
false Default value - no preference

Examples:

Deliver the mobile device presentation of a web site to a desktop device

1.4 Terms Used in the Definition of the User Preference Properties

The following terms are used in the definitions in this specification:

alternativeText
Text that is programmatically associated with non-text content and that serves the equivalent purpose (WCAG2).
  • http://www.w3.org/TR/WCAG20/#text-altdef;
  • http://www.w3.org/TR/WCAG20/#text-equiv.
audioDescription
Narration that has been added to a soundtrack to describe important visual details that cannot be understood from the main soundtrack alone (WCAG2). Note that in some countries this is referred to as 'videoDescription'
  • http://www.w3.org/TR/WCAG20/#audiodescdef.
Might be further refined as enhanced.[to be done link to defn of enhanced]
auditory
Information is conveyed that requires the sense of hearing.
May be refined with the detail recorded or synthesised
blackOnWhite
black text and borders on a white background
captions
Synchronized visual and/or text alternative for both speech and non-speech audio information needed to understand the media content (WCAG2):
  • http://www.w3.org/TR/WCAG20/#captionsdef
Might be further refined as enhanced or realtime [TDB link to defns]
e-book
Electronic book, a book published in electronic form:
http://en.wiktionary.org/wiki/e-book
flashing
A visual pattern that flashes more than three times in any one second; this level of flashing can cause seizures in some users (WCAG2 Guideline 2.3.1 A):
  • http://www.w3.org/TR/WCAG20/#seizure
flashingStrict
A visual pattern that flashes more than three times in any one second; this level of flashing can cause seizures in some users (WCAG2 Guideline 2.3.2 AAA):
  • http://www.w3.org/TR/WCAG20/#seizure
haptic
Of, or relating, to the sensation of touch; used here to identify resources that include force feedback or other three-dimensional interfaces:
  • In part from http://www.webopedia.com/TERM/H/haptic.html.
Linguistic Indicator:
highContrast
Visual presentation of text and images of text that has a contrast ratio of at least 4.5:1, or, for larger text, a contrast ratio of at least 3:1 (WCAG2 Checkpoint 1.4.3):
  • http://www.w3.org/TR/WCAG20/#visual-audio-contrast.
inverseVideo
Text, image and video colors reversed
longDescription
An alternative text that is longer than a few sentences.
motionSimulation
Content that simulates motion; this may result in a feeling of nausea to the user.
signLanguage
A language using combinations of movements of the hands and arms, facial expressions, or body positions to convey meaning (WCAG2):
  • http://www.w3.org/TR/WCAG20/#sign-languagedef.
simplePresentation
A presentation of a similar level of complexity to that commonly delivered to small screen devices using agile design - typically no more than six controls or regions of interest on a page.
sound
An audio pattern that can cause the user to have seizures [ISO 29138].
tactile
Information is conveyed that requires the sense of touch.
textual
Information is conveyed that requires the processing of text
transcript
A written, typewritten, or printed copy; something transcribed or made by transcribing: http://dictionary.reference.com/browse/transcript.
visual
Information is conveyed that requires the sense of vision.
whiteOnBlack
white text and borders on a black background

1.5 Term Refinements

Some terms, when used as values of a property, may have accompanying detail refinements or parameters giving further preference detail.

enhanced
An adaptation with more extensive forms of alternative than the standard for that kind of adaptation; enhanced captions might include images or speech bubbles, and enhanced audio description might pause the video to insert extra audio.
realTime
An adaptation produced at the time a resource is being produced; real-time captions are often used for live newscasts.
recorded
An audio adaptation featuring a human voice reading the material.
synthesized
An audio adaptation featuring text-to-speech technology.
verbatim
An exact transcription of audio; verbatim captions or verbatim transcripts capture all speech word for word.


1.6 API, Data Structures and Implementation Strategies

[TO DO]

1.7 Possible Future Work

 Preferences for personalisation of educational assessment ?