Discretising the AB2 L-2 Π 𝑢 -mode configuration 𝒞 ̅ 2 space gives the directed graph shown in Fig. where edges are annotated by transforming generic symmetries. The simple undirected graph version of the directed graph is given in Fig. . Table summarises composition. Of the AB2 L-2 Π 𝑢 -mode 𝒞 ̅ 2 configuration space. From the perspective of a polytopal rearrangement, that is, no breaking of making of bonds to the central A-atom, the two hemispherical chambers of the AB2 L-2 Π 𝑢 -mode 𝒞 ̅ 2 configuration space are disconnected as any trajectory between the hemispheres must pass through the equatorial hyperplane resulting in changes of coordination number. Each the hemispheres of the AB2 L-2 Π 𝑢 -mode 𝒞 ̅ 2 configuration space comprises a distinct "ABn-stereoisomeric domain" and the space is said to be ABn-stereoisomerically disconnected.