Siegel cusp form (awaiting review)

A Siegel modular form Siegel modular form $f$ with character $\psi$ and weight $\rho$ on an arithmetic subgroup $\Gamma \leq \GSp(2g,\Q)$ is called a cusp form if for any $\gamma\in \Sp(2g,\Q)$, we have $\Phi(f|_{\rho}\gamma)=0$ where $|$ is the slash operator.