Unlike virtual folders, which are made up of searches that dynamically find components, folders have a physical model through a parent-child relationship with the components they contain.
A folder class defines the folder model to be created. Its specificity is the notion of the child.
Children
The folder class defines which child classes it is authorised to contain.
As many as possible can be defined. If you need to contain all the classes of a component type, for example, all the documents, you can add a child with the identifier * as follows:
<ns2:children category="DOCUMENT">
<id>*</id>
</ns2:children>