building .debs with "+b1" on the end

[Brian Sammon <debian-users-list@brisammon.fastmail.fm>]

I want to re-build a package for personal use, and have a special version number for my custom build.

Since I'm not planning on customizing the source or the debian control files, I think the ideal choice is to build a binary package with a suffix like "+b1" or "+local" on the end.

An example of this sort of thing is the current wheezy package of "libcrypt-blowfish-perl"
(https://packages.debian.org/wheezy/libcrypt-blowfish-perl)
As near as I can tell, the 2.12-1+b2 .debs of this package was created after the 2.12-1 .debs, but from the same source code, and without creating an entry in the changelog.

How would I do this?  I've looked in various places, and I can't find any relevant documentation.