A traffic manager generates {HEAD ~ a tree scheduling hierarchy} having a root scheduler and {TAIL ~ N scheduler levels} 
A traffic manager generates { HEAD ~ a tree scheduling hierarchy } having a root scheduler and { TAIL ~ N scheduler levels }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL