Function bridgeable 

pub fn bridgeable(from: &VersionNumber, to: &VersionNumber) -> bool

Available on crate feature convert only.

Whether this build can translate documents between two OCPI versions.

Today that is exactly the 2.2.1 ↔ 2.3.0 crossing, in both directions, plus the trivial case of a version to itself. It is a function rather than a constant because the answer depends on the Cargo features the crate was built with.