I have written a paper attempting to describe how Adobe managed the evolution of the PDF file format for over 15 years before turning its management over to ISO. I have offered this to the ISO committee so that they may benefit from Adobe's experience, but we are still trying to figure out the appropriate ISO publishing mechanism to make it available from them. In the meantime it will be available here.
Adobe tried very hard to allow new PDF files with new features to be viewable in older viewers. Likewise, we tried to design our viewers so that when they were the "old viewer" they would do the best that they could to display a file even if it had new features. And perhaps most important of all, we almost never removed any feature from PDF so that any file could be viewed by today's viewers even if the file was made 16 years ago.
This paper was derived from an internal Adobe technical note written by me and a task force of employees who studied the whole issue of versions and compatibility in 2006. I have acknowledged those other employees at the end of the paper. Thanks to them.
That paper is, of course, a PDF file and is attached here:
Enjoy! (Oh, and I almost feel like I should apologize for not making more regular posts to this blog. I have just been very distracted with several things. Hopefully I can find more time in the future.)
Jim King <mailto:firstname.lastname@example.org>