Re: TIFF-FX: technical changes since RFC 2301

> > Presumably there is a good reason to have tiff-fx contain this redundant
> > capability.  So, presumably, there are times when it IS a good thing to use?
> >
> > When is that?  And can we make the recommendation be clear about the
> > circumstance in which -fx use of the redundant profiles is discouraged,
> > versus when it is ok?

> Hmm.
> As we already have "image/tiff-fx", basically, the implementers must use it.
> It became formal last September. As we expect easily,
> every implementers do not follow the latest information.
> It takes much time.

We have two types now. tiff-fx does indeed have to be used for profiles other
than S and F; this is a given. The question is what label should be required
for profiles S and F. I think it is reasonable to ask agents to use the more
specific label image/tiff whenever possible. I also think it is reasonable to
allow the use of image/tiff-fx when information about the actual profile
being used isn't available.

There is ample precedent for this sort of thing in MIME, BTW. Take the case of
charset labelling, where US-ASCII is a strict subset of various other charsets
like iso-8859-1. It is simpler for an agent that supports iso-8859-1 natively
to simply label everything as iso-8859-1. However, RFC 2046 states that if only
the US-ASCII repetoire is employed by a given object the more specific subset
label of US-ASCII SHOULD be used to label that object. The more general
labelling is allowed but not encouraged.

				Ned