Energy term diagram of the Coriolis coupled ν₂/ν₄ dyad for the rotational states up to J=2, K=1. Unperturbed (F_ab = F_ab,c = F_ab,J = F_ab,K = 0) and perturbed energy terms are drawn as horizontal solid lines with the J rotational quantum number displayed only for the unperturbed level. States subject to Coriolis interaction are connected by grey dashed arrows. Slanted dashed colored lines connecting energy levels show the energy shifts resulting from the Coriolis interaction.