  In a recent paper (2018), D. Hofmann, R. Neves and P. Nora proved that the
dual of the category of compact partially ordered spaces and monotone
continuous maps is a quasi-variety - not finitary, but bounded by $\aleph_1$.
An open question was: is it also a variety? We show that the answer is
affirmative. We describe the variety by means of a set of finitary operations,
together with an operation of countably infinite arity, and equational axioms.
The dual equivalence is induced by the dualizing object [0,1].
