Coordinate system

1992, D. H. Maling, Coordinate Systems and Map Projections, 2nd Edition, Pergamon Press, page 27, In this chapter we review some of the fundamental ideas about the plane coordinate systems which are used in surveying and mapping, both from the viewpoint of studying the mathematics of map projections and the practical tasks which arise in cartography.

Note that the orientation of Squire's coordinate system relative to the physical coordinate system is changing as a function of wavenumbervector.

In Chapter 1 the choice of the origin and orientation of the analysis Cartesian coordinate system was made arbitrarily.[…]Note that nothing was said about the origins of the above two Cartesian coordinate systems.