2002.07.25 00:58 "embedding metadata in TIFF and JPEG/JFIF images", by Bill Comstock

2002.07.25 01:13 "Re: embedding metadata in TIFF and JPEG/JFIF images", by Chris Cox

Unfortunately, anything beyond baseline TIFF makes the files more vulnerable to application failures/bugs.

No matter how simple a change you make, and no matter how carefully you document that change, it will break somebody (or somebody will break it!).

But XMP is no more dangerous than anything else in that regard (since it is self contained).

EXIF is a bit more risky in that it cannot generally be round-tripped (the EXIF tags may be undocumented, and are thus impossible to preserve). EXIF also has problems in that it does not correctly support Unicode strings.