I've prepared a new draft that has procedures for reading and writing
raw strings. `write-fancy` or something like that could be implemented
with those procedures.

 > Since the procedure can see the whole string, it can choose the tag
by itself.

I decided against adding a procedure that would automatically infer a
tag, because the approaches I thought up to automatically generate the
tag were either very complicated or had pathological behavior that could
be used for a DoS attack.

If someone wants to have automatically generated raw string tags they
will have to write that procedure themselves because they understand the
trade-offs of their own use-case better.

-- Peter McGoron