A
system of representation, usually formalistic.
Characterized by having a discrete side usually a discrete
end.
The attributive (adjectival)
use of "complex" is identical to its functional (nominal) use.
A complex usually has a discrete end but no discrete beginning. Quantum mechanics is an archetypal example of a complex
system.
Musical notations are an example of a complex
system that has a discrete beginning but no discrete end.