In the current PURE implementation, all epilogues are
equally qualified for execution. This is enforced by employing
a simple FIFO queuing strategy when an epilogue
needs to be made pending. When being executed, any of
these epilogues may ask for the scheduling of a process of
a higher priority than the currently executing process. As
a result, the current process will be preempted in favor of
the execution of some higher-priority process. Whether or
not that process really is of the highest priority, and, thus,
preemption at that moment was the right decision, depends
on the actions performed by the subsequent epilogues in the
queue.