libpq backwards compatbility

We have a libpq application written in C++. There are existing running deployments of our application that were compiled against PostgreSQL version 9.3.

We want to move to PostgreSQL version 9.6.

Can we assume that the 9.6 libpq library is backwards compatible with applications compiled against 9.3 headers? I wouldn't expect to have to re-compile our application against 9.6 libpq headers and redeploy because we're not taking advantage of any new features and nothing seems to have been deprecated.

The release notes talk about additions to libpq in section E.2.3.9 "Client Interfaces". I'd expect any un-changed features to be backwards compatible. Limited testing suggests this is so but I can't find a clear statement.

Could somebody please advise?

Thanks

Andy