CPN model consists of a set of modules, each of which contains a network of places, transitions and arcs. The modules interact with each other through a set of well-defined interfaces, in a similar way as known from many modern programming languages. The graphical representation makes it easy to see the basic structure of a complex CPN model, i.e., understand how the individual processes interact with each other. Throughput is a measure of the actual data that can be sent per unit of time across a network, channel or interface. Throughput is more often used in a practical sense, for example, to measure the amount of data actually sent across a network.