When a process calls DosWaitChild and blocks waiting for a child process to terminate, the BlockId is of the form:
ffcapppp where pppp is the process id of the waiting
thread.
The BlockId doesn't help us pin-point the processes being waited for.
All the child process have to be examined. The process status byte at offset 0xa into the Local information segment has either of the following bits set if the parent cares about termination of the child:
0x10
The local information segment is embedded in the PTDA at the following offsets:
0x7ee