versioning and version indicators in PDF

A colleague, Jim King,   submitted a note about the methods used for
managing versioning of PDF, as a contribution to the ISO PDF
standard (PDF ownership has moved to ISO, and the committee
is considering a new version after ISO 32000-1, I believe).

The paper:
 http://blogs.adobe.com/insidepdf/Compatibility_090819.pdf

Referred to Jim's blog entry:
http://blogs.adobe.com/insidepdf/2009/08/pdf_evolution_and_compatibilit.html

Although there are differences between PDF and HTML
in deployment, the compatibility goals (new versions of
software handles old files, old software gracefully handles
new files) are quite similar.

Larry