Binding AccessForAll Properties to schema.org Classes
One of the goals of Access For All (AfA) metadata is to improve the findability of resources that meet individual user needs. This page describes a proposal for extending schema.org classes with AfA-compatible properties. schema.org is a collaboration between major search engines to develop and collect shared microdata formats to improve search results.
The Access For All metadata standard was designed to be used in conjunction with existing metadata standards and specification. The intention is that existing metadata can be supplemented with additional properties containing the AfA information. schema.org defines classes for common resource types and is already being used to describe those resources. One of the recommended approaches to extending the specification is to add properties to existing classes.
The general way that schema.org microdata works is as follows:
- the
itemscope
attribute is added to the container of the thing being described. (In the case of HTML5 videos, this would be the<video>
element. In the case of images, a container must be placed around the<img>
tag.) - the
itemprop
attribute is added to information within the container. Typically, you might wrap the text of a name, for example, in a<span>
with itemprop="name". The AfA information is not meant to be displayed. In this case, the<meta>
element is used with the combination ofitemprop
andcontent
attributes.
What would this look like in an Authoring Tool?
The primary resource types currently of concern within an OER authoring tool include images, videos and the document as a whole.
Notes on AfA metadata
- a value of
false
for anis-
orhas-
property implies that it is known definitively that the resource "does-not-" or "has-not-." If it cannot be known definitively one way or the other, the property should be omitted. In the comments below, I'm considering things we can infer automatically, not things an author can specify through direct knowledge.
Sample Image Markup
<div itemscope> <img src="http://foo.org/img.png" alt="alt text here"/> <meta itemprop="has-alt-text" content="true"/> <meta itemprop="has-long-description" content="false"/> </div>
Sample Video Markup
<video itemscope src="http://foo.org/img.png"> <meta itemprop="has-caption" content="true"/> <meta itemprop="has-transcript" content="true"/> </video>
Sample Document Markup
<body itemscope> <meta itemprop="is-mouse-accessible" content="true"/> <meta itemprop="is-keyboard-accessible" content="true"/> <meta itemprop="is-display-transformable" content="font-size font-face foreground-colour background-colour"/> <meta itemprop="has-hazard" content="false"/> ... </body>
Full Property List
Properties on CreativeWork (a parent class of articles, images, videos, etc)
Schemas use inheritance (multiple, in fact). Properties defined on CreativeWork will be inherited by ImageObject, VideoObject, etc.
Property |
Expected Type |
Description |
Comments on application to OER Authoring Tools |
---|---|---|---|
is-mouse-accessible |
boolean |
The resource can be controlled using the mouse alone, if necessary |
Assume always true for OER-as-a-whole |
is-keyboard-accessible |
boolean |
The resource can be controlled using the keyboard alone, if necessary |
At OER level: always true; At per-video level: true if our player, unknown if Flash. Summary should combine all. |
is-display-transformable |
Text |
vocabulary: font-size, font-face, foreground-colour, background-colour |
At OER level: all present; At per-video level: all present for our player, none present if Flash/youtube. Summary should combine all. |
has-eBook |
boolean |
an eBook alternative is available |
Known false at OER level. |
uses-colour-coding |
boolean |
The resources uses colour to convey information. |
Unknown at all levels. |
has-hazard |
Text |
vocabulary: flashing, sound, olfactory, motion simulation |
Known to have NO hazards at OER level and at image-level; unknown at video level. Summary should combine all. |
has-text-representation* |
boolean |
a textual alternative is available |
Normally, this is in reference to a specified original access mode. For OER authoring tools, we should use the refinements applicable to more specific media types, such as "captions" |
has-audio-representation |
boolean |
an auditory alternative is available |
False at OER level, unknown at image and video level. |
has-tactile-representation |
boolean |
a tactile alternative is available |
False at all levels |
has-visual-representation |
boolean |
a visual alternative is available |
|
has-audio-description |
boolean |
an audio description of the visual content is available |
|
has-caption |
boolean |
a text caption of the auditory content is available |
|
has-e-book |
boolean |
an e-book alternative is available |
|
Properties on ImageObject
Property |
Expected Type |
Description |
Comment on application to OER authoring tools |
---|---|---|---|
*has-alt-text |
boolean |
this resource has alt text available |
|
*has-long-description |
boolean |
this resource has a long description available |
I'm not sure if we can know this one. |
Properties on VideoObject
Property |
Expected Type |
Description |
Comment on application to OER authoring tools |
---|---|---|---|
*has-transcript |
boolean |
this resource has a transcript available |
|
has-sign-language |
boolean |
a sign-language translation of the auditory content is available |
We can't know this one definitively. |
Where Properties Are Recorded In Web Content
Note: If something is "unknown," the metadata property should be absent (not false, not empty).
Note: Even if properties are always unknown, that fact will be summarized and so OER should be scanned for the property anyway.
* = scanned and summarized in "General" section of display
** = not sure how to summarize this one
On the OER describing the text, not including images or videos
Property |
Assessment |
---|---|
*is-mouse-accessible |
always true |
*is-keyboard-accessible |
always true |
*is-display-transformable |
always all values |
*has-eBook |
always false |
*uses-colour-coding |
always unknown |
*has-hazard |
always present but empty |
On Images
Property |
Assessment |
---|---|
*uses-colour-coding |
always unknown |
has-alt-text |
true or false |
has-audio-representation |
always false (technically, it's unknown, but false for this iteration) |
has-long-description |
always false (technically, it's unknown, but false for this iteration) |
On Audio Files
Property |
Assessment |
---|---|
has-transcript |
always false(technically, it's unknown, but false for this iteration) |
has-visual-representation |
always false (technically, it's unknown, but false for this iteration) |
On Videos
Property |
Assessment |
---|---|
*is-mouse-accessible |
always true |
*is-keyboard-accessible |
true for our video player, unknown for youtube/Flash |
*is-display-transformable |
all values for our video player, present but empty for youtube/Flash |
**has-caption |
true or false depending on UniSub query; |
has-transcript |
always false (technically, it's unknown, but false for this iteration) |
*uses-colour-coding |
always unknown |
*has-hazard |
always unknown |
has-audio-description |
always unknown |
has-visual-representation |
always unknown |