I am reading Ramakrishnan – Database Management Systems 3rd Edition, and they are using a version of Chen Notation to draw ER diagrams, with that said all the resources I have found do not use arrows and instead use ratios such as 1 to many or many to many. I am trying to understand what the arrows mean in this diagrams, alternatively sources which discuss this version of the Chen Notation would also be appreciated.Chen Diagram

I have tried searching for resources online and reading the text book, but have not found any concrete documentation regarding the specific details of this version of Chen Notation.