1. Computer apparatus for model-to-model transformation, comprising: a plurality of model transformations, each model transformation receiving models having a respective input model format and generating models having a respective output model format; and respective bridges between pairs of the model transformations in a series of the model transformations, for each pair of consecutive model transformations in the series, the respective bridge (i) receiving a model output from a first model transformation of the pair, the received model being in the respective output model format of the first model transformation, (ii) preparing the received model as input to a second model transformation of the pair, including preparing the received model to be in the respective input model format of the second model transformation, and (iii) inputting the prepared model to the second model transformation of the pair; such that the series of model transformations and respective bridges provide chaining of model-to-model transformations.