An indexing and registration shown is maintained whereby {HEAD ~ the location} of {TAIL ~ any particular container} within the entire tiered grouping of containers is known at all times 
of
An indexing and registration shown is maintained whereby { HEAD ~ the location } of { TAIL ~ any particular container } within the entire tiered grouping of containers is known at all times
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH