You can search for identifiers within the package.
in-package search v0.2.0
module type Intf = sig ... end
type 'value t = (module Intf with type value = 'value)
type ('value, 'tag) with_tag = (module Intf with type tag = 'tag and type value = 'value)
module Unimplemented : sig ... end
module Make (B : Intf) : sig ... end