This facet is motivated by the importance of access to the latest changes and stable releases of the tool. We consider the update time to be regular if the tool is updated at least once a year. If the tool does not follow a regular update schedule, we indicate its update time as sometimes. We consider the update time to be discontinued if the tool is no longer offered or is no longer being updated. The update time of these tools is usually limited to the initial development period, with only rare updates after the first release. Similarly, we describe the update time as replaced, if the tool was replaced by a successor. 

Comparison of Model Transformation Tools