R906 - modelint/shlaer-mellor-metamodel GitHub Wiki
R906 / 1:Mc
Flow establishes zero, one or many Flow Dependency
Flow Dependency is established by exactly one Flow
A Flow Dependency defines the path of a Flow from one Action to another.
Not all Flows originate at an Action. A Class Accessor, input Parameter, and executing Instance Flow, do not originate in an Action and are consequently not part of any Flow Dependency.
If a Flow originates as an output of some Action and is then input into multiple Actions, each input will result in a distinct Flow Dependency.