Embodiments are directed to implementing a dynamically changeable system model that is customizable per version, programmatically generating system models at runtime and to extending a programmatically generated system model. In an embodiment, a computer system determines that a dynamically changeable system model corresponds to a managed system. The dynamically changeable system model includes various managed system objects. The computer system indicates for the dynamically changeable system model which managed system objects are available in each version of the managed system. The available managed system objects are stored in a data store of the dynamically changeable system model. The computer system requests the managed system to provide current managed system information including at least a version identifier and, based on the managed system information indicated by the managed system, provides to the dynamically changeable system model those managed system objects that are provided by the indicated version of the managed system.