Re: text/*

> My understanding of top-level types is that image, audio & video indicate 
> what the stream encodes, whereas text (and perhaps message) indicate how 
> the stream is encoded. For instance, 'text/vnd.abc' encodes audio, but is 
> encoded in text.
no, that's not how it's intended to work.  for all cases, the top-level
content-type describes the underlying content, not the encoding.
the content-transfer-encoding field describes the encoding.