Managing spec files

[Matt Ford]

Hi All,

I am looking at building a fedora package.  I have been over guidelines 
and taken a look at the build system.  What I am not clear on is how I 
maintain spec files for different distributions i.e., F12, F11, F10, or 
even EPEL.

Do I have to branch and maintain each spec file separately or is there a 
better way?  Are there any tools that abstract the commonality?  Do 
people try to write spec files that work on any distro with conditionals?

Thanks for any wise words,

Matt.