Local formatting databases can be overridden by formatting rules passed over the wire, expressed in Abstract Syntax. In reality, formatting databases may need to contain Expert System-level sophistication to be able to produce professional quality typesetting results, but we believe that useful results can be achieved even without such sophistication. Note that Abstract Syntax is human-readable. Many will want to interact only with mathematics that has a textbook-like appearance, and they should be able to do so. We do not agree that such a distinction can be made.
Meaning is just a handshake between sender and recipient.
Help and status queries, the replies to help and status queries, and error messages should be read and written by SMC's in Abstract Syntax. In general, it is permissible for two SMC's to use private protocols for communication. Our example of a tightly coupled ED and DISP above is one example. To qualify as SMC's, however, they should be able to translate all such exchanges into equivalent exchanges in Abstract Syntax.