As Mermaid supports ER diagrams, I would like to propose that Extended Entity Relationship Diagrams should be supported, such as double lined rectangles (framed rectangles are not double lined!), ...

Physical EXTENDED Entity Relationship Diagram Level extends the original ERD by showing super-subtype entities. In this case, department and employee are the supertypes and the subtypes inherit their ...

In this paper, we present a process that extracts an extended entity relationship diagram from a table-based database with little descriptions for the fields in its tables and no description for keys.