Description of Relationships in ERD

Unfortunately, there is no description of the relationships of the database tables in the entity-relationship diagram. The user does not see what the lines (solid or dashed) and the points (round or square) mean.
Although this information could be found out from the information schema somehow, a direct display in the ERD would be much more helpful.
I think it would make most sense to add a legend or some kind of tooltip when hovering or clicking the cursor.