  We present dynamic measurements of a lattice gas during phase separation,
which we use as an analogy for self-assembly of equilibrium ordered structures.
We use two approaches to quantify the degree of 'reversibility' of this
process: firstly, we count events in which bonds are made and broken; secondly,
we use correlation-response measurements and fluctuation-dissipation ratios to
probe reversibility during different time intervals. We show how correlation
and response functions can be related directly to microscopic (ir)reversibility
and we discuss time-dependence and observable- dependence of these
measurements, including the role of fast and slow degrees of freedom during
assembly.
