Thank you.

I see what you're saying. The characteristics are a consequence of the actions it performs or receives (the essential interactions).

But I considered it important to discuss them, to make background for discussing the other things in the parts to come. Things such as constructors.

I will definitely bear your comment in mind as I write. Thank you so much.

Emmanuel Aliyu

Great !

Remember full constructors are very important to favor immutability.

So I guess your point will be to link those constructors to what you call characteristics, but even that is accidental.

To store (or not) these essence in characteristics is a design decision.

You can ask for Cartesian coordinates when building a point but store in polar format. This decouples the behavior (be a point) to the accidental characteristics (store as x and y).

This is very difficult to understand to beginners since they mostly care about implementation.