Assume that x and y are of type DATE:
1. AGE( x, y ) < INTERVAL '...' works.
2. x < y + INTERVAL '...' works.
3. x - y < INTERVAL '...' doesn't work (but then, the minus operator is not
defined in the manual for two DATE values).
Question: Is the meaning of x - y well-defined? That is, is there a
definition that I can count on?
Not an important question, but I'm curious, since I like to write date
differences in a style that makes readability/maintenance easy.
-- Dean
