R1201 - modelint/shlaer-mellor-metamodel GitHub Wiki

R1201 / 1:Mc

Instance Set Action takes a input from exactly one Instance Flow

Instance Flow provides a input to zero, one or many Instance Set Action

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Each set operation requires two Instance Flow Inputs and we'll refer to them arbitrarily as the a and b inputs. In the case of the union and intersect operations, there's no distinction between the two. For the difference operation, however, the references in the b input are subtracted from those in the a input.

Any given Instance Flow may provide input to any number of Instance Set Actions or none at all.