The extant theory for interrelationships among stratospheric trace constituents is largely based on tracer kinematics in the meridional plane. As such the theory relies on a zonally averaged model, and hence a compact relationship is granted a priori in the horizontal. Relatively little has been theorized beyond the zonal symmetry despite the fact that interrelationships are constructed routinely from point-by-point measurements rather than zonal average. In this paper we will investigate tracer interrelationships in the horizontal (isentropic) plane. Robustness of compact relationships will be tested under various flow regimes and processes that cause scatter will be quantified. Assuming that a compact relationship exists on each isentropic surface, we will derive an equation that governs this relationship. It is shown that the solution to this equation includes the well-known extratropical slope equilibrium and chemically controlled tropical pipe regime as special cases.