Typo in comment
'plainpage' style was not needed --- the marking at the end of SF298 was not a bug.
Because the abstract was FOUO, the SF298 was getting marked -- which is the
correct behavior. I interpreted this as a bug, invented the new pagestyle as a work-around.

Have removed the style, changed the page to plain, and added a new example
showing the behavior when we have a marked Abstract and when we don't.
This is "nice" and "clever" and "correct." I hope we don't break it in the future.