States are propagated up the hierarchy. The state of a parent is governed by specific rules of precedence based on the states of the children. The rules of precedence are as follows:

     cancelled -> error -> processing -> waiting -> not initiated -> successful

For example, given the hierarchy shown below:

         

the following would describe how the states of the children affect the state of the parent:

     If  B is in error and C is successful, A is in error.

     If  B is waiting and C is cancelled, A is cancelled.

     If  B is processing and C is not initiated, A is processing.