Which property must be assigned to allow data to flow into a process when it is initiated?

The property that must be assigned to allow data to flow into a process when it is initiated is the process variable. Process variables are essential in Appian as they define the data that can be accessed and manipulated within a process instance. When a process is initiated, any incoming data that needs to be utilized within that process is stored in process variables. This allows the process to receive and work with external data, leading to appropriate decision-making and task execution based on the information provided during initiation.

In contrast, the other options do not fulfill the role of facilitating data flow into a process. Alerts, for example, are used for notification purposes and do not contribute to the initial data setup of a process. The process name serves as an identifier for the process itself and does not handle incoming data. Node output pertains to the data produced by specific tasks within the process, but it does not define how data is received when starting a new process instance. Thus, process variables play a crucial role in ensuring that processes have the necessary data at their inception.