I have a "global variable" XML schema in TIBCO BusinessWorks. It's simpler than it looks - basically just a single repeatable node.

Image: Tibco globals.
(old URL redacted)

Various processes in the system can update this list. Checking to see if they are listed is easy:

$GetVariable/subscriber-list/subscriber = $_processContext/ns:ProcessContext/ProcessId

Adding themselves to the list is pretty easy too, using a Set Variable activity (see bottom half of image)

But how can a process remove itself from the list? I'm sure there's a type of mapping I can use to filter out the node I want and let the rest through?