I am trying to understand a jump diffusion process of peter tankov. I studied economics, so i don't understand a lot about stochastic calculus. At a certain point, i have this equation:
$\frac{dC_t}{C_{t-}}=mdZ_t+\left(1-m\right)dR_t$
And after applying ito's lem:
$ \frac{dC_t^\star}{C_t^\star}=m(dZ_t-d[Z,R]_t-dR_t+d[R]_t)$
What the brackets mean? What kind of processes are this? Thanks a lot!