An alarm event occur only once, unless it is modified by a

repeat every

attribute.

A message event can occur multiple times. For example, while an order is being processed inside a scope, changes for the order can be accepted via a message event.

Multiple message and alarm events can occur concurrently. If your process contains two concurrent scopes with shared variables and event handlers, be sure to enable

isolated

for the scopes. Enabling this ensures consistent access to shared variables.