This is the first deliverable of the RDRIWG, the Research Data Repository Interoperability Primer. It presents the targeted use cases as well as an overview of standards, technologies and tools this WG has expertise in and which are potentially a part of the proposed consensus. The main focus of the document is on machine operable interfaces, but it also contains a comprehensible collection of data and metadata formats and models focusing on the exchange of digital content in a generic way. Finally, a selection of custom tools is presented, which might not be adopted, but can support decisions through the experience gained while developing and using them. The present document will serve as a basis for discussions towards a consensus to be accepted by a majority of WG members and platform developers in order to achieve a broad adoption of the WGs' outcome and to make progress toward research data repository interoperability.