Aspects of Charmonium

Here we discuss three separate topics in charmonium physics. (1) The Omicron \OMC as $1^{--}$ trigluonia, and the charmonium puzzle; the $\eta_c' (3600)$ search. (2) The decay $\psi(^1P_1) \to \pi^o + J/\psi$ and isospin violating charmonium decays. (3) How to search for $\chi_c' = \chi_c(2P)$ charmonium states.