Linked from here are draft individual proposals for extending the Schema.org vocabulary. The intention, as they are each individually agreed, to merge them into a combined proposals set to form a proposal to the group managing extensions to the Schema.org vocabulary.
Work-Instance- Renamed to CreativeWork Relationships
- CreativeWork Relationships - as proposed by this group
- citation - Accepted
- Audiobook - Proposed
- Collection - Proposed
- Holdings - Using existent Schema.org properties and types: Holdings via Offer