<release-version-id> ISO-Specific Release Version ID
Typically used for CEN and CENELEC, this element contains the technical key (unique identifier) in the CEN PROJEXDATA (a service that allows CEN NSBs to download essential project data in XML format) that identifies a standard release version. The CEN standard release version is the version of a standard which corresponds to a major stage of progress of the standard development process (milestone).
The <release-version-id> can be useful for linking to other metadata sources (i.e. PROJEXDATA).
This element is currently specific to ISO-related Regional standards processing and is provided for reasons of backwards compatibility. It has always been allowed inside <reg-meta>, and it is now allowed inside other elements to provide ISO Regional users with a migration path to using <std-meta> without metadata loss.