ConstReadonlyNone: "none"No incoming edge (root)
ReadonlySubject: "subject"Element is the subject of a node
ReadonlyAssertion: "assertion"Element is an assertion on a node
ReadonlyPredicate: "predicate"Element is the predicate of an assertion
ReadonlyObject: "object"Element is the object of an assertion
ReadonlyContent: "content"Element is the content wrapped by another envelope
The type of incoming edge provided to the visitor.
This enum identifies how an envelope element is connected to its parent in the hierarchy during traversal. It helps the visitor function understand the semantic relationship between elements.