[Indicates] the physical similarity and relationship between the members of a set, e.g. trees may occur in a collection of the same species, of different species, or even in a patternless collection with plants that are not trees.[18] [Category] 
Configuration
C o n f i g u r a t i o n
A f f i l i a t i o n
P e r s p e c t i v e
E x t e n s i o n
E s s e n c e
C o n t e x t
D e s i g n a t i o n