p is causally related to q if and only if p or any part of p and q or any part of q are linked by a chain of events where each event pair is one of direct activation or direct inhibition. p may be upstream, downstream, part of or a container of q.

Chris Mungall

http://purl.obolibrary.org/obo/ro/docs/causal-relations

Do not use this relation directly. It is intended as a grouping for a diverse set of relations, all involving cause and effect.