I wasn't thinking of "error-codes' but rather "status codes". An ID of a resource, running on the web could unify it uniquely, not really the physical machine b

I wasn't thinking of "error-codes' but rather "status codes". An ID of a resource, running on the web could unify it uniquely, not really the physical machine but the server-application we are talking to. But maybe it's enough that we have URIs?