The encoded word has the encoding as one of its 3 required parts. If
you want to use the encoded word to explicitly identify a 7 bit
character set, say iso-2022-jp, with the current specification you
would be required to specify one of "b"inary or "q"oted printable when
neither is necessary.
Yes, but iso-2022-jp *does* need to be encoded in either "B" or "Q"
since (a) it uses ESCAPE (0x1b), and (b) it often uses bytes that are
"dangerous" in headers (i.e. "<", "(", <">, ",", etc). In fact, some
of the Japanese even want to mandate "B" for iso-2022-jp since it's so
safe and since it takes a fair amount of trouble to figure out *which*
byte values would need to be encoded if the "Q" encoding was used.
I repeat: The motivation for the "7" encoding is to *allow* for
charsets *like* MU, which are already safe in headers as is.
Erik