http://mimesniff.spec.whatwg.org/#determining-the-sniffed-media-type-of-a-resource

This algorithm is confusing. Section 4 defines "sniffed media type" as the result of invoking an algorithm, but then that algorithm reads that value. It looks like the algorithm really should be reading and writing to a "local variable", and then returning that, or, that the term shouldn't be defined outside that algorithm such that the algorithm should just be called directly by referencing specs.