What is a mapping node

What is a mapping node

In a given minimal model, a mapping node is a node which contains exactly two references to two other nodes, thus defining a many-to-many relationship between the two entities defined by the referenced nodes.

Example:

rifle model                    // Entity A
    name

magazine model                 // Entity B
    name

rifle model magazine model map // Mapping node
    rifle model                  // Reference to Entity A
    magazine model               // Reference to Entity B