These terms appear to have become purely honorific, although they may originally have denoted special equipment or ethnic composition (gentiles were barbarian tribesmen admitted to the empire on a condition of military service).

A further variation encountered in computer science is the Z notation: is used to denote the traditional (right) composition, but ⨾ (a fat semicolon with Unicode code point U+2A3E) denotes left composition.

Like in C, the semicolon denotes sequential composition: stands for "run statement then run statement .

Here denotes vertical composition of natural transformations, and denotes horizontal composition.

Whereas the automorphisms of a single object form a group, the set of isomorphisms between two isomorphic objects naturally forms a heap, with the operation (here juxtaposition denotes composition of functions).

Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.