Invariant
A rule nobody can switch off — including us. Enforced in the engine, not the interface.
Settings are yours to tune. Invariants are not tunable by anyone, because switching them off would make AutoPPC capable of a category of mistake it should never be able to make.
Examples: never negate a term whose conversion family has orders; never re-enable something you paused yourself; never judge a change before its attribution window closes; never move a bid and a placement modifier on the same campaign in one run.
They are listed in full under Settings › What AutoPPC will never do.