I think that what @PaulClarke is getting at is that, while PDF that is compliant with the standard can be opened in multiple PDF viewing/editing programs, and is platform independent, this document is not able to be opened by anything other than Adobe Acrobat. There may be different reasons why, for example document security settings or proprietary components embedded into the document. From a user perspective, that looks like a “proprietary” format. I can’t state that it’s not compliant with the ISO standard because I suspect there’s a section that addresses how to handle document security within the ISO framework.
As long as we’re throwing out ideas, I’d love to see the document created in LaTeX (mostly because I’m not quite enough of a Nerd to manage to do it in TeX). :^)