Application shell levels: understanding the hierarchy

The community members are discussing the meaning of "Level 1", "Level 2", and "Level 3" in the context of Application Shells. One community member believes this refers to the respective Z heights of the components, while another community member assumes that in the case of Application Shell 8, Level 3 is the side navigation, Level 2 is the header, and Level 1 is the main content. However, there is no explicitly marked answer provided.