When you create a package, the server assigns Default for the List ACL. (Packages do not have Read, Write, or Execute ACLs). This means that any authenticated user can see that the package exists.

When you create a top-level folder, that is, one that is not contained in another folder, the server assigns Default for the List, Read, and Write ACLs, and Internal for the Execute ACL to the folder. This means that any authenticated user can see that the folder exists. The Read and Execute ACLs have no meaning for the folder itself. They are there just for inheritance purposes. In other words, elements in the folder will inherit those settings.

When you create a subfolder or other element (service, schema, specification, document type, trigger, and other elements) the folder or other element inherits its ACL setting from the parent folder.