Normative reference to schema.org in EPUB Accessibility?

Ralph, Philippe,

this type of question comes up regularly, but I did not see any clear cut answer.

The EPUB Accessibility spec[1] has a section on package metadata[2] to refer to metadata like access mode or accessibility features. The specification defines these terms in general, meaning that it is not properly defined which terms are to be used in a real metadata instantiation; this is left to the separate WG Note on a11y techniques[3] which reveals the thinly veiled fact that, in practice, these general terms refer to their equivalents in schema.org <http://schema.org/>[4]. Indeed, all the terms defined in [2] are, actually, defined in schema.org <http://schema.org/>, and those are the only mappings for those terms. Those terms are not out of the blue, actually: they have been developed, originally, in cooperation with the IMS Global[5] and are now maintained on [6].

The reason of this somewhat weird setting in [2] is to avoid normatively referring to schema.org <http://schema.org/>.  Actually, the accessibility spec has an earlier version published at the ISO, and in ISO land it was a clear no-no to do so. However, W3C is meant to be more flexible and therefore the question does arise. However, our document on normative references[7] is not 100% clear cut for me. 

Hence this mail: does W3C has an official position as for a normative reference to schema.org <http://schema.org/> terms? Specifically, is it possible to simplify [1] and make a clear reference to schema.org <http://schema.org/> instead of the hand-weaving approach we have there currently? In case of a positive answer, can we, possibly, add a reference to schema.org <http://schema.org/> in [7] just as we do with the WhatWG?

Thanks for your help

Ivan


[1] https://www.w3.org/TR/epub-a11y-11/ <https://www.w3.org/TR/epub-a11y-11/>
[2] https://www.w3.org/TR/epub-a11y-11/#sec-disc-package <https://www.w3.org/TR/epub-a11y-11/#sec-disc-package>
[3] https://www.w3.org/TR/epub-a11y-tech-11/#meta-002 <https://www.w3.org/TR/epub-a11y-11/#sec-disc-package>
[4] https://schema.org/accessMode <https://schema.org/accessMode>
[5] http://www.imsglobal.org/activity/accessibility <http://www.imsglobal.org/activity/accessibility>
[6] https://www.w3.org/wiki/WebSchemas/Accessibility <https://www.w3.org/wiki/WebSchemas/Accessibility>
[7] https://www.w3.org/2013/09/normative-references



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Ivan Herman, W3C 
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