More on REST and HTTP status codes

What status should a server return for a request such as

http://example.com/catalog?product=0001

if the resource that identifies the catalog (example.com/catalog) is
available but cannot find the product identified in the query string?

The question boils down to whether an HTTP URI is opaque or if the
question mark has predefined semantics. (The specs would have me
believe the former, but the practice seems to be the latter).

Ari.

-- 
Elections only count as free and trials as fair if you can lose money
betting on the outcome.