Let $A = [0,1]\times[0,1]\times[0,1]$, $r\colon A \to \mathbb{R}$ and $v\colon A \to \mathbb{R}$.
What is the most clear and standard notation for the integral $\int\limits_D r\,\mathrm{d}V $, where $D = \{ (x,y,z) | (x,y,z) \in A, r(x,y,z) > r_0,v(x,y,z)<v_0\}$, and $r_0$ and $v_0$ are constants?