You can search for identifiers within the package.
in-package search v0.2.0
module V2 : sig ... end
module V3 : sig ... end
module V4 : sig ... end
The V4 bin_io representation is the same as that of V3, but its sexp representation is the same as that of the unstable type, i.e. a human-readable, decimal string.
V4
V3