At 08:54 -0800 20 Mar 2000, Professional Software Engineering
A digit in that position originally meant the number of rules to
follow. Recipe parsing was subsequently revised, and the digit didn't
need to specify the number of rules, and so the common convention is
to specify '0'.
The historical reason is correct (after the above substitution), but
that's not quite how it works now. The number is now the minimum number
of conditions. There can then be additional conditions after that. For
the most part this distinction can (and should) be ignored, but it does
mean that using 0 isn't just a convention, using a different number
could produce different results.
Aaron Schrab aaron(_at_)schrab(_dot_)com http://www.execpc.com/~aarons/
C makes it easy for you to shoot yourself in the foot. C++ makes that
harder, but when you do, it blows away your whole leg. -- Bjarne Stroustrup