Address Popup in Compose

[lists@nvethis.d2g.com]

I'm trying to add the address patch by Michael Cochrane to my Horde 2.0 IMP 3.0 installation.  I'm having trouble understanding what I need to 
replace in the specific files her defines?  I am not quite sure what I need to replace or if I actually need to add these lines?  I'm not sure how 
to read CVS.

What is the signifigance of these lines:
diff -I$Horde -I$Revision -I$Date -r2.123.2.6 compose.inc
300a301
???

I'd appreciate any help you guru's can give.  I have found a few patches that I'd like to try and adapt to my Horde/IMP Framework, but am not quite 
sure how to go about.  Thanks.

Bryan