Classification of Phenomena

For the development of a system, it is very important to distinguish between the part of a system that already exists, the environment, and the part of a system that has still to be developed, the machine. Each phenomenon and also each term has to be uniquely assigned to either the environment or the machine.

Based on the distinction between environment and machine, phenomena/terms are classified further w.r.t. the following two aspects:

control:	It is demanded that each phenomenon/term is controlled either by the environment or by the machine.
visibility:	It is demanded that each phenomenon/term controlled by one of these parts is also visible to this part.

We say that a phenomenon belongs to the part it is controlled by. Note that a phenomenon/term can be visible to both parts.

From these constraints concerning control and visibility, the following kinds of phenomena/terms can be derived:

eh, ev, mh, and mv denote the scope of a phenomenon/term. It is required that each phenomenon/term has exactly one of these scopes.