Term Kind Topic What it is
Boundary Reversal Asymmetry Split Reversal Cost, Asymmetric Boundary Error concept Service Boundaries The fact that a boundary drawn too coarse is cheap to split later while one drawn too fine is expensive to merge, which makes the coarse error the right default when evidence is thin.
Invariant Containment Boundary Follows the Invariant, Transaction Test concept Service Boundaries The rule that a service boundary must contain any invariant that must hold exactly - so discovering that a split would break a transaction is evidence the boundary is wrong, not merely an obstacle.