I, I
I, I : The symbol I is used to indicate that part of a ray path that has traversed the Earth's inner core as a P-wave. On the other hand, i is used to indicate reflection at the boundary between outer and inner core in the same manner that c is used for reflections at the core-mantle boundary. For this and other such symbols used in seismic phase names see IS 2.1 in this Manual and Storchak et al. (2003 and 2011)