A storage represents a system which serves as an accumulator of mass or energy. A storage function can have any number of connections and any num- ber of enabling conditions. An example could be the function of a tank when used as a device for accu- mulation of a fluid, in this example we are dealing with a mass storage. Another example could be the storage of energy in a boiler by heating the water.
A storage has at least one input
A storage has at least one output
A storage must have one transport as input
A storage must have one transport as output
A storage can have both multiple inputs and outputs