These subsystems of ArgoUML are infrastructure subsystems that just are there for every other subsystem to use - but they are not using any other part of ArgoUML.

Low-level subsystems have a simple dependency structure: All other ArgoUML packages may depend on them, but there are no dependencies "upwards", nor between them.

This latter statement is the way to recognize a low level subsystem: it does not depend on any other argouml package.

All these subsystems are started and initiated (if needed) from the Application subsystem, see Section 5.13, “Application”.