Called Processes
Checkpoints save the state of the entire process instance. By default when a process calls another process, the subprocess is executed in the same process instance as the calling process. If the called process spawns a new machine process, however, the called process is a new process instance.
When a checkpoint occurs in a called process, the checkpoint saves the state of the current process instance. If no called processes spawn new process instances, then a checkpoint in any called process saves the state of the process instance, including state from the parent process(es) of the current process. In the case of a called process that spawns a new process instance, only the spawned process instance is saved.