Thanks for the explanations.
It can be very confusing when things change, apparently by magic, but those changes are important to the operation of a moderated forum.
Is there a feature in IPB which can generate a message to the authors of posts which are deleted (or edited) by a moderator?
I mean something relatively automatic, which could perhaps prompt for a comment to attach, but would not require the moderator to do more work in addition to everything they're already doing. If not, that might be a good feature to suggest to Invision for a possible future release.