Article 21 covers devices for special purposes (custom-made, investigational). Article 22 covers systems and procedure packs - combinations of MDs or MDs with non-MD products (system / procedure-pack producer signs a declaration that the components are compatible + bear CE marking + the combination is properly sterilised where applicable). Article 23 covers parts and components placed on the market separately for replacement / repair / refurbishment.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.