Overall the changes between OPDS 0.9 and 1.0 are relative minor, and migration of OPDS 0.9 Catalogs to 1.0 should require minimal attention:
- OPDS Catalogs are now more generic to open the door to other electronic content in the future (audio/video, comics etc.)
- References to indirect acquisition have been removed. Discussions will continue outside of the core specification in an information document.
- There is a new "rel" value for Open Access.
- Artwork relations have been modified.
- The definitions and groups feed-level relations have been morphed into: sorting relations, popular relation, previously acquired relations, and crawlable feed relation.
- There is a notation relating to the use of DRM: "Publications in a format using Digital Rights Management SHOULD use a different value for the type attribute of the Acquisition Link than the same format without Digital Rights Management."
- See additional specification language about the relationship between summary/content.
- There is an informational Relax NG schema.
Overall, these numerate fairly minor modifications and should not require too much work to support them.
For a closer examination of changes, please consult the OpenPub wiki.