A relationship between a continuant and an occurrent, which holds if and only if at every time an instance of the occurrent is created, it has at least one instance of the continuant participating in it at the same time.

Smith B, Ceusters W, Klagges B, Kohler J, Kumar A, Lomax J, Mungall C, Neuhaus F, Rector AL, Rosse C: Relations in biomedical ontologies. Genome Biol 2005, 6: R46.