In https://github.com/edx/edx-platform/pull/25955 `HiddenDescriptor` (which was a subclass of `RawDescriptor` with a custom `student_view()`) was converted to an XBlock. It is used as the `default_class` by the `CachingDescriptorSystem` classes. However `RawDescriptor` is still being used by `XMLModuleStore`. This has been replaced by `HiddenDescriptor` as well.
CMS (Content Management System) ------------------------------- This directory contains code relating to the course management portal for edX, also known as Studio.