|  You will need something to resolve that "service" then.
|  Have fun coding a pkg manager!

  Let me summarize my (probably not quite ripe yet) brainstormed ideas.

  Suppose we have some packages

	sendmail (provides "service-MTA")
	exim (provides "service-MTA")
	cron (depends on an "service-MTA" being present)

  When one installs sendmail/exim, it registers an additional package
"service-MTA" (or whatever, I'm not attached to those names), which
depends on the package just installed (ie. sendmail/exim).

  When you deinstall sendmail/exim, the service-MTA package will go
too because of the dependency.

  Suppose I have installed sendmail and try to install exim, then
the package system should check whether a "service-MTA" is already
installed and warn me of a conflict (just like we have today, just
the conflicts don't have to be explicitely named -- simplifies things
quite a bit).

  Things dependent on the service package could just use normal
dependencies.

  This does not sound all that difficult. Is any crucial part
missing?

	mjl