Update: The information below is "OBE"; it has served its purpose. All of the doc nodes which were in category 2 have been converted to devdoclets, and the respective calling codes have been modified to call showdevdoclet instead of showsitedoclet. In fact, all remaining uses of showsitedoclet have been converted, and it is now completely obsolete. Category 1 doclets are retrieved with get_sitedoclet only.
Each extant sitedoclet is categorized as to whether it is:
These are displayed when viewing the code of the associated node -- even in the cases where the node is a superdoc. Thus, they are only ever seen by pmdev (and gods).