 Armstrong (1986) admits that the composition of structural universals is non-mereological. In his 1997, he emphasizes that states of affairs do not have a mereological kind of composition, and views universals, including structural ones, as states of affairs-types which, as such, are not mereological in their composition. Structural universals themselves turn out to be state of affairs-types of a conjunctive sort (1997: 34 ff.). To illustrate, let us go back to the above example with H2O exemplified by the water molecule \(w\). It involves the conjunction of these states of affairs: