Book features vs system features

[madeleinerothberg]

I was asked to write some language to better explain the lack of ONIX crosswalk for Schema.org metadata properties that applies to reading systems and not to books. Here are proposed changes to the current Note at the top of the ONIX section, with square brackets like this [ ] marking the place I suggest adding the new sentences. I also suggest some words to delete for clarity in the last sentence about ONIX 2.0. This issue of system vs. book properties may also be relevant to EPUB, in which case we could consider putting a similar note elsewhere in the document.

ONIX does not have an exact 1:1 mapping with EPUB accessibility metadata so unfortunately not all of the accessibility metadata found in an EPUB exists in ONIX at the time of this publication. There are plans to add this metadata to future versions of ONIX but no time frame has been announced. This EPUB to ONIX crosswalk outlines the current overlap in metadata which will get updated as these two specifications evolve. [add Some Schema.org metadata properties, referenced in EPUB, are descriptions of reading systems and not individual books; this means they will not be appropriate for use in ONIX and will not have a crosswalk. This includes the property "bookmarks" which indicates the ability of a reading system to allow users to set and navigate to bookmarks.] It is important to note that there were a number of new accessibility metadata codes added to ONIX 3 to support the Accessibility 1.0 specification. [delete Which means that] ONIX 2 has a limited number of accessibility metadata codes and is [delete something] not covered in this document.