Use case for different "World Center Mode" implementation

Hi there! Thank you for reading my post.

I am always wondering why Vuforia, in Unity implementation especially, give us an option to change the WORLD CENTER MODE. As it being explained, it has there modes: 1) DEVICE, 2) FIRST_TARGET, and 3) SPECIFIED_TARGET. All of them are easy to understand by their name, but if someone look at this post and don't have a quite understanding, you can check at https://developer.vuforia.com/forum/unity-extension-technical-discussion/what-world-center-mode?sort=2.

My question is can you give me some examples of these three WORLD CENTER MODE in real case?

E.g., In Virtual Historical Museum, we use DEVICE mode so the World coordinate origin is refer to the camera position, so the virtual object can easily imagined their relationship to the smartphone camera.

Thank you in advance.