The d3d flag is documented, just not on that page. Check outhttp://java.sun.com/j2se/1.4.1/relnotes.html
Yes, reading the release notes can sometimes be useful =)
There's a bunch of undocumented flags, but we generally don't encourage people to use them because most of them are unsupported and can go away at any release, so we can't have people rely on them.
But they're quite useful for debugging purposes, so we're thinking about having them documented, or even have an ability to list them all at runtime if asked. Say,
would print all the flags and their descriptions.
Would something like that be useful?
We're currently planning on adding this in our next major release (which won't be available any soon, unfortunately).