I've just applied a large number of changes to the sgml docs contributed
by Vince Vielhaber. These mostly add "tag completion" to the markup as
required by the newest versions of docbook and the style sheets.
The content changes are minimal; I've added mention of the "NULL" column
constraint to be added to gram.y (not yet committed though; waiting to
get some more outer join parser stuff ready).
The changes required a good bit of time and effort to do; thanks Vince!
- Tom
