Hello, FWIW I do not share Andrej Shaduras view on this. My interpretation is basically the opposite. The invoke-rc.d, policy-rc.d and update-rc.d policy mandated abstraction is solely for the use of maintainer scripts in debian packages (and should not be used by init systems or elsewhere).
Note also that the 'service' utility abstraction, which is supposed to be for (interactive) administator usage also does not care about policy-rc.d (as designed). Regards, Andreas Henriksson