The second kind of delay, inertial delay, is used to model devices which
do not respond to input pulses shorter than their output delay. An intertial
delay is specified by omitting the word transport from the signal
assignment. When an inertial delay transaction is added to a projected
output waveform, firstly all old transactions scheduled to occur after the
new transaction are deleted, and the new transaction is added, as in the
case of transport delay. Next, all old transactions scheduled to occur before
the new transaction are examined. If there are any with a different value
from the new transaction, then all transactions up to the last one with a
different value are deleted. The remaining transactions with the same
value are left.