ViewModels (Views) are perspectives on part of the information available in the model. The ViewModels can be used for defining a user interface (UI) but can just as well define the information available to a REST-api or the data available in a report.
You may use the AutoForm-technique to rapidly create ViewModels to browse EVERYTHING in your current model.
All ViewModels must state what Class they are typed to, but a ViewModel must also state if it is Rooted in an object of that class (it is given access to a specific instance object from your Class, this is your typical Document - Screens) - or not rooted (it must find its information on type level - grabbing things from "thin air" rather that having something to start with - this is your typical seeker - that helps user find objects they can show in rooted document screens).