The Bundle Protocol is an end-to-end protocol for the exchange of messages in Delay Tolerant Networks (DTN). Version 6 of the Bundle Protocol was published 2007 as an experimental specification in RFC 5050. After gaining experience from different implementations of this experimental specification, version 7 was published as an Internet Draft in 2016.
I have compared those two versions of the Bundle Protocol during a student research project. The result and the complementary presentation can be downloaded here.