Every relationship has exactly one source and one target, each an element, a relationship, or a connector. A relationship must not link two relationships; a connector must join only links of one type; a junction chain is permitted only where the same direct link would be permitted between its end concepts; and a link from an element to another relationship is limited to aggregation, composition, or association, with aggregation and composition running from a composite element. Composition, aggregation, and specialization are permitted between same-type elements, association is permitted between any two elements or between an element and a relationship, and any relationship that would otherwise be ambiguous should carry an explicit name or label.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.