OData version 4.0 specification was approved by the OASIS OData Technical Committee as a Committee Specification in August of 2013.
The public version of the proposed committee drafts are below. Start with Part 1: Protocol for an overview of the OData Protocol. See Part 2: URL Conventions for details on the URL syntax, and Part 3: Common Schema Definition Language for details on the OData Modeling language. Finally, refer to OData JSON Format or OData Atom Format for details on the individual payload formats.