
135Implementation
A queue can function simply as a place to wait in an organized matter.
A normal queue is one where the rst entity to enter is also the rst one to
be served by the resource (i.e., rst in, rst out). For health care facilities, a
very common type of queue is one where priority is accorded based on an
attribute value or via an expression that makes it possible to rank individuals
on the urgency of their need. Much less common are queues where last one
in is the rst one out. Apart from organizing the waiting and prioritizing
who gets to use the resource, queues can also provide useful information,
either as an output (e.g.