Thinking through Mike's last e-mail:

We do have a mechanism for expressing a binary term in CQL via
relational modifiers which is what I'm doing in the music context set.

Returning binary data in the response records is easy I just specify a
record schema that includes base64 or mimeEncoded data

I hadn't really thought about scanning a index on binary data but it is
plausible (pictures or audio being obvious ones) - again the CQL
relational modifier works well in sending the request. However I can't
return the binary data as the term/value element. I could put something
reasonable in there and return the binary in the term/extraTermData?

Alternatively we relax term/value to be xs:ANY and add a term/schema
value (as per record/data, record/schema)?

Matthew