  The study of concurrent persistent programs has seen a surge of activity in
recent years due to the introduction of non-volatile random access memories
(NVRAM), yielding many models and correctness notions that are difficult to
compare. In this paper, we survey existing correctness properties for this
setting, placing them into the same context and comparing them. We present a
hierarchy of these persistence properties based on the generality of the
histories they deem correct, and show how this hierarchy shifts based on
different model assumptions.
