Databases:	=
Files in Git - as at Github.com/CommonAccord/NW-NDA/	=
JSON, XML.	=
Graph databases, conventional databases. IPFS and blockchains.	=
Really Technical:	=
Mirage, OCaml: All data and code understood as git repos. https://github.com/mirage/irmin	=
Which leads back to the question, could a transaction system - for instance a financial system - be organized in a decentralized manner as git repos and pull-requests? Might that address the problem that blockchains address, without many of the disadvantages? Is there an intermediate layer that is needed (Corda or other)?	=