Thank you for this interesting discussion topic!
A new version of Ace was released last week that addresses the printPageNumbers and pageBreakMarkers issue: https://github.com/daisy/ace/releases/tag/v1.3.2
According to W3C “printPageNumbers” is not formally deprecated and can still be used, but “pageBreakMarkers” is the recommended value.
As for “pageBreakSource”, while it is being developed as a replacement for dc:source and page-source properties, it is not formally part of EPUB 3 and might produce a validation error with epubcheck. The following DAISY Knowledge Base page will be updated once the use of “pageBreakSource” is fully recommended: http://kb.daisy.org/publishing/docs/navigation/pagelist.html#pbs
Moreover, for extended descriptions that exist on a separate xhtml page within the EPUB, the accessibility feature “longDescription” is typically used, particularly for complex content such as images, tables, charts, etc. The “annotations” value is used when the “publication comes with explanatory annotations that improve the accessibility of the work” from the “author, instructor, and/or others.”
See the following links for more on these accessibility features:
July 19, 2023 at 3:59 pm