Each subsystem also includes {TAIL ~ a blocker} coupled to a DA and associated with {HEAD ~ a home directory} 
Each subsystem also includes { TAIL ~ a blocker } coupled to a DA and associated with { HEAD ~ a home directory }
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD