Scope note: This property associates an instance of E4 Period with another instance of E4 Period that is defined by a subset of the phenomena that define the former. Therefore the spacetime volume of the latter must fall within the spacetime volume of the former. This property is transitive. Examples: - Cretan Bronze Age (E4) consists of Middle Minoan (E4) In First Order Logic: P9(x,y) ⊃ E4(x) P9(x,y) ⊃ E4(y) P9(x,y) ⊃ P10(y,x)