1. A computer method for model transformation reapply, comprising the processor executable steps of: through a programming model transformation in MDA (Model Driven Architecture), generating a target model having one or more model elements, the target model being a UML-type, graphical, program modeling model that generates executable code; marking parts of the target model as non-changeable by inserting into the generated target model respective annotations to the model elements indicating which parts are non-changeable by the programming model transformation and thus preservable, each annotation: (i) having an indication of extending the respective model element, and (ii) specifying extra semantics of extending the respective model element, for each annotation, the annotation specifying the extra semantics by any combination of: a string-to-string map, a containment reference collection and a non-containment reference collection; reapplying the programming model transformation to make changes to the target model but preserving manual changes made to the model elements based on the extra semantics specified by the inserted annotations; and wherein reapplying the transformation further includes configuring the transformation with an option to detect deltas between newly generated target models and existing target model, and select which deltas to apply and which to ignore as a function of the inserted annotations.
3. A computer method as claimed in claim 1 wherein reapplying the transformation further includes configuring the transformation with art option to override existing target models with contents of newly generated target models.