1. A method of checking consistency between a first computer-represented graphical model and a second computer-represented graphical model, the method comprising: obtaining model correlation information that defines at least one relationship type between the first model and the second model and which comprises a mapping of objects of the first model to objects of the second model; and ascertaining, using at least one processor, an inconsistency between extant versions of the first model and the second model using the model correlation information including the relationship type.