Use this activity as criterion for your push action if you want to cast the push update only once per execution run. If this criterion is not added, the push receiver will be notified every time about updates.
Example
When using a PushContent Activity, the clients will be notified about every update of each property value of the UBIK® object. With this activity as a criterion, the notification only happens once and the point in time when the push is cast can therefore be influenced exclusively by the author of the workflow.