Sometimes you need globally unique identifiers, such as for ISRCs. One way to approach this is by using URIs – the uniqueness of the domain part of URIs is administered by ICANN, the uniqueness of the rest of the URI is administered by the owner of the domain. There’s a good balance between centralization and decentralization.
But ownership of domains changes, and when it does the identifiers associated with one ownership become invalid. Many types of identifiers, including ISRCs, need to be persistent. So you couldn’t use URLs for these.
This could be corrected by adding a date to the identifier. The new identifier would be a URL/date pair, like
[“January 1, 2000”,”http://example.com/1234”]
The date specifies a point in time when the identifier was valid. So if there is a valid identifier http://example.com/1234 on January 1, 2000, and then example.com comes under new management which doesn’t support this identifier, the dated URL continues to be valid.
This only works for URIs used as identifiers and not for URIs used as locators. Adding the date would not restore an old URI that was out of service.