[p3-payload] Media-Type -- Two Values, One Cup Anti-Pattern?

Hi,

I had a question about the evolution of media types.

Early media types constrained themselves strictly to describing the format
(syntax) of the representation (image/png, application/xml).  As time wore
on, though, media types sprang up that contained both syntactic & semantic
type information (see the application/vnd.openxmlformats-*+xml series for
an example).  Negative ramifications seem obvious (add json, yaml => m*n
types, parsing, querying, ...); in fact, in other contexts (DB & object
fields), placing two values into a single cup/bucket is such a basic
mistake with such obvious drawbacks, it's rarely even discussed as an issue.

Does anyone else see this as a problem?

Media types of this sort are being created to solve a problem, though.  I
believe they may indicate an unsatisfied need to specify not only syntactic
type, but also semantic type in a uniform way.  Which would present the
more uniform interface?


   - Each implementer creating custom headers & custom registries for these
   data types
   - Header & registry defined by a fantastic standards body :-)

At any rate, thanks for all your hard work & genius.  Apologies if this
isn't the proper forum/format/approach/timing/anythingelse.

Regards,
Ray