Systems can be structured hierarchically using links which have a direction. The link, however, cannot be established directly between two systems.

While components may be subordinated directly to one another, a subordinated system is not linked directly to its superior system. Instead, it is linked to the superior system's particular usage type (Usage Type of a System).

System Hierarchy: Each system must be assigned to at least one usage type (print server, data server, web server). Each link between a system and a usage type is called Usage Type Of System.

If a subordinated system needs to be linked to a superior system, it will be linked to the superior system's Usage Type of a System. Each individual link between one subsystem and one usage type of a superior system is called Two Systems Relationship.

Example: Let's consider two usage types: data server and print server, system A (superior) and system B (subordinated). System A is used both as a print server and a data server. System B uses system B's "print services" only, thus is linked only to the 'print server' Usage Type of System A.

Usage Type Of a System and Two Systems Relationship function as linking objects and both of these links are time-related. Using our example again, system A may be used as a print server for a certain limited period of time only (given by valid from/valid to of Usage Type of a System), system B may be using these print services for a time interval within this period (equal in length or shorter) (given by valid from/valid to of Two Systems Relationship).

New links are set up starting from current date, removed links are ended by day before the current date. User can change the assignment dates and add comments to each link (by double-clicking on an assignment).