p 'causally upstream or within' q iff (1) the end of p is before the end of q and (2) the execution of p exerts some causal influence over the outputs of q; i.e. if p was abolished or the outputs of p were to be modified, this would necessarily affect q.

p is 'causally upstream or within' q iff p is causally related to q, and the end of p precedes, or is coincident with, the end of q.