The  Elementary Graph domain defines the basic constructs for relating and classifying Elements in a directed graph.

 SysFEAT is based on a node-centric definition of graph that follows the principal of lexical locality.

It defines the concepts of entity (Entity Element) and relationship (Relationship Element) as specific kinds of nodes.

To implement the principle of locality in graph definitions,  SysFEAT has adopted a layered approach of relationship formalization:
1) It starts by explicitly encoding directed edges as Kuratowski pair ,  <a,b> = { {a}, {a,b} }, represented as: Adjacency List.

2) Adjacency Lists are then reified to create direct relationships between Entity Elements: Relationship Elements.

3) Further structuring of Entity Elements and their Relationship Elements is provided by the Compositionality pattern that layouts the concepts of locality and connections.