Support for embedded annotations in packaged publications

[HadrienGardeur]

Now that Thorium (and therefore Readium Desktop) has support for embedded annotations on its roadmap, this should also be on the mobile roadmap to ensure cross-compatibility.

The first step will remain the definition of a shared format, but the core idea is already scoped:

• when opening an EPUB that contains embedded annotations, they should be parsed by Readium Mobile and made available to integrators that would like to support their presentation in their app
• and Readium Mobile needs to provide an easy way to export and update annotations and store them in a packaged publication

Given the importance of Locators in Readium projects, we can expect these APIs to be built on top of them.