b occurs in c =Def b is a process or a process boundary & c is a material entity or site & there exists a spatiotemporal region r & b occupies spatiotemporal region r & for all time t, if b exists at t then c exists at t & there exist spatial regions s and s' where b spatially projects onto s at t & c occupies spatial region s' at t & s is a continuant part of s' at t
Example
A process of digestion occurs in the interior of an organism; a process of loading artillery rounds into a tank cannon occurs in the interior of the tank