Continuing from my previous post, when 2 or more planets (Moon included) are extremely close in Equatorial latitude, they are "in harmony" when they're on the same side, north or south of the Equator (parallel). And, "in disharmony" when on opposite sides (contra-parallel).This affects their relationships when it comes to longitudinal conjunctions, oppositions, and aspects.
For example, they can be in longitudinal conjunction, or trine, but not harmonious if contra-parallel. And in opposition or square, and still be harmonious if they're parallel.