emdebian-changelog.patch -
implements the emdebian version change by calling
debchange.
emdebian-control.in.patch -
may be absent if the package does not use
debian/control.in.
emdebian-control.patch -
removes documentation and installer packages and maintains any other
changes to the dependencies of the packages.
emdebian-rules.patch -
maintains all changes to the rules for cross-building the
package.
There is also a Wiki page of useful snippets to add or modify
debian/rules.
http://wiki.debian.org/EmdebianGuide