2000.10.06 16:13 "RE: PDF is NOT proprietary!", by Ed Grissom
My apologies for speaking from ignorance. I have found the PDF File Format document on Adobe's site, and it appears that all that is required to R/W PDF is a Copyright notice in your application. In that respect, it is slightly different from TIFF.
Although my point is still valid about other companies, it may not be true about Adobe.
Perhaps I was too quick to jump on Adobe due to their complete dismissal of all of my many attempts to ask for information on, or to be able to contribute to, some discussion of TIFF 7.0.