In this fullerene the plane of symmetry bisects three six-membered rings indicated as A, B, and C in Fig. 29a. Ring A contains two 6,6,6 atoms, and is therefore preferred to begin the numbering over the other six-membered rings that contain only 6,6,5 atoms (Fu-126.96.36.199). Of the six pathways to be considered from ring A (clockwise and anticlockwise from a, b, and c), only those proceeding anticlockwise from a and anticlockwise from b lead to contiguous numberings. The former, shown in Fig. 29b, begins at an atom 0.5 bond away from the reference plane; the latter (Fig. 29c) begins at an atom 1.5 bonds away from the plane. According to Fu-3.3.3a, the former (Fig. 29b) is correct.
Fig. 29. Systematic numbering of (C70-Cs)[5,6]fullerene