2000.10.10 08:41 "Re: IFD / Image data ordering", by Brian Stafford
Sheesh. How did RFC 2301 get accepted?
RFC 2301 mandates a *profile* of TIFF which must be used by conforming TIFF writers and which is fully compliant with the TIFF 6.0 specification. The reason for the forward reference only rule is so that the TIFFs are usable by limited memory devices which cannot buffer entire files prior to processing. Such devices are expected to become commonplace in the Internet Fax appliance market and one of RFC 2301's goals is not to prohibit such devices.
IIRC, TIFF 6.0 states that compliant readers must be prepared to handle any ordering of the structures within a TIFF but does not mandate any ordering of the internal structure while writing a TIFF. An RFC 2301 TIFF writer is therefore also a TIFF 6.0 writer, however an RFC 2301 reader is neither required to be, nor prohibited from being a TIFF 6.0 compliant reader.
Obviously they carefully refrained from allowing it to be reviewed by anyone with a clue about TIFF.
The IETF FAX working group has considerable TIFF expertise; the WG has additional constraints which do not apply in other TIFF applications.
Brian Stafford, OfficeLogic International Ltd.
PGP fingerprint: 23DE 0A02 95B2 EC3C D521 0CD1 97D8 6BF2 B673 DC11