RPM file name standard?

[Joe Desbonnet]

Is there a document that defines the format of a RPM file name for the
 Fedora project?

For example consider these RPMs:
ImageMagick-perl-6.2.2.0-3.fc4.0.i386.rpm
ImageMagick-perl-6.2.2.0-3.fc4.1.i386.rpm

I'm puzzled about the significance of the numbers 0 and 1 following
".fc4." in these update
RPMs.

Thanks,
Joe.