The rise of the model as a rst class entity in the eld of software engineering, sparked an intense period of research into the design and development of model transformations in the 1990s and 2000s. This thesis is about a particular kind of model transformation, in which the source and target models are ordered by containment. It asserts that the monolithic proof of correctness of an ordered set of transformations is equivalent to the sum of the proofs of its elemental parts. It also demonstrates by means of a type theoretical solution that the assertion is sound.