Concerns about Guidelines for Creating Entity Relationship Models

Question

I am currently enrolled in the online Oracle Academy Database Design Course, which briefly talks about the concept of nontransferable relationships. I understand the concept behind them, but the course's vague details left me with a few of questions.

1. Can nontransferable relationships exist between entities which are connected with a 1:1 or M:M relationship? All of the example provided by Oracle depicted 1:M relationships.

2. Can the diamond used to represent the nontransferable relationship be drawn on either end of the relationship, whether they are optional or mandatory? I believe they can only appear on the mandatory end of the relationship, but I want to be sure.

3. Similarly, can the diamond used to represent the nontransferable relationship potentially appear on BOTH ends of the relationship?

The following are a couple of examples provided by the Oracle Academy:

Answer 1

1. I'm not sure but if you think about certain 1:1 relationships, they are nontransferable. For example, one person can only have one passport. A passport cannot be transferred between people. I'm not sure about many to many but I can think of an example - you can have a group of people who write series of books. This would be many to many and authorship cannot be transferred to other people. That probably isn't a great example.

2. The diamond can be drawn on either side but typically it appears on the mandatory end, so I would always put it on that end.

3. I have never seen the diamond on both ends.