By enactment we are referring to any system, whether automated or followed by humans, which carries out an organisation's processes. Using enterprise models to assist in enacting an organisation's processes can be of benefit both at time of establishing or at time of changing such processes.
Having taken the trouble and the expense to create the model for insight or communication, an organisation does not want the added expense of creating separate models to help in building its enactment systems: it makes sense to reuse the same model.
Reuse also helps to ensure consistency between the model of what is supposed to happen and what really does happen in the enactment systems. If this consistency can be achieved, then change can be initiated by changing the enterprise model. If the generation of enactment systems from enterprise models can be automated, then so much the better.