And to respond to your implied criticism: the stability/reliability/fidelity of PDFs is a myth. It would be hard to say how many dozens of PDFs I've come across in the last two years that don't look the same across devices/viewers (or sometimes just fail to render in their entirety). This played a significant part in a cascade of errors in one incident I know of that resulted in the payout of a claim more than $1,000 but less than $10,000—not to mention a lot of strife and anger for the persons involved over the course of multiple months before resolution.

(As I write this now, I realize I'd almost forgotten about the fact that almost every time I've taken something to FedEx or UPS to be printed at a self-service kiosk, the result has been unusable, so I've had to take it to the clerk to have them print it instead.)

HTML at least has the property that it's still trivial to access and extract the data if you run into either malformed inputs or ones that are valid but incompatible/unsupported by whatever viewer (browser) you happen to be using, which is a lot more than you can say for more opaque formats like Java, PDF, and Flash.