Thus like prior art prior clock subtree models, a subtree model in accordance with the invention depicts the maximum and minimum delays between the root of a subtree and the sinks connected to the subtree as functions of the transition times of {HEAD ~ the rising and falling edges} of {TAIL ~ the clock signal} as it arrives at the root of the subtree 
of
Thus like prior art prior clock subtree models , a subtree model in accordance with the invention depicts the maximum and minimum delays between the root of a subtree and the sinks connected to the subtree as functions of the transition times of { HEAD ~ the rising and falling edges } of { TAIL ~ the clock signal } as it arrives at the root of the subtree
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