While on holiday in the south of France, I’ve spent some of my relaxation time delving further into the mathematics of valve modelling in preparation for some more software development when I return. As a consequence, my understanding of the work of the likes of Derk Reefman and Norman Koren has certainly improved dramatically. I have now provided some commentary to these models here (along with some very minor improvements) in case this may be helpful to those also wishing to get under the skin of these models.