Bruce> This is going to be a backward compatibility problem, but
Bruce> to support ANSI syntax we are going to need to do this.
Given the existence of the INTERVAL '1' MONTH etc syntax is completely
undocumented, I doubt it's a major problem.
(Actually, INTERVAL '1' and INTERVAL '1:30' are undocumented, too, but
it's probably more likely that people are relying on that).
-roy