R56

R56 / 1:Mc

Process Output Port feeds zero, one or many External Output

External Output consumes exactly one Process Input Port

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An External Output cannot receive input directly passed through by an External Input without any intermediate processing. And an External Output cannot directly access a Store. So the only possibility left is for some Process's output to be provided externally via an External Output.

This leaves the question of whether or not an External Output must provide content. It seems reasonable to assume that if an External Output is defined, it should produce at least the empty set as output. It is then up to the client as to whether or not to make use of the output.

Formalization

External Output.(Process output, Graph, Content) ->
    Process Output Port.(Name, Graph, Content)

By referencing the super-identifier we ensure that the Content defined for the External Output matches that of that incoming from the Process Output Port.