System software is a specialization of a node that is used to model the software environment in which artifacts run. This can be, for example, an operating system, a JEE application server, a database system, or a workflow engine. Also, system software can be used to represent, for example, communication middle-ware. Usually, system software is combined with a device representing the hardware environment to form a general node.
A device or system software can be assigned to other system software; e.g., to model different layers of software running on top of each other. System software can be assigned to artifacts, to model that these artifacts are deployed on that software. System software can realize other system software. A node can be composed of system software.
The name of system software should preferably be a noun referring to the type of execution environment; e.g., “JEE server”. System software may be composed of other system software; e.g., an operating system containing a database.