http://fedoraproject.org/wiki/NewPackageProcess
says:
Patches should start at Patch0, don't use Patch, even if you only
have one
right now, because inevitably, you'll need another one at some point
before the sun explodes.
What is the rationale?
Patch: foo.patch
Patch1: bar.patch
# ...
%patch -p1 -b .foo
%patch1 -p1 -b .bar
work just fine. 'Patch' == 'Patch0' is true.