This schema allows responses with more than one classification (each with its own URI, that is, each should be able to be requested individually). The uri element in this response is the actual request (the one that returned this response): in this case it's redundant because only one classification was requested.
Of course, more metadata can enrich this basic schema (updated, general label or description, family vocabulary, standard name...), as it is the case for the rest of the JSON-stat elements described so far.
Big classifications shouldn't be retrieved with the data every time new data are available: JSON-stat categories responses should provide enough information for caching purposes (like, if available, expiration, probably not only in the response header).
Here is the same example