When looking at 372148, I found out that my maintainer scripts diagrams had the same bug that Policy currently has.

Also, these diagrams used to document a bug in dpkg, regarding the state a package was left when removed or purged; which was fixed long ago, but I had never had the time to update them accordingly.

Tonight, finally, I've updated them. And I've also made my test-suite package much more tidy, so that now I can publish it for anyone to grab it, and use it to test which maintainer scripts are called in some particular case. The dia sources, the png images, and the packages I used for the tests are all available here.