These materials are best read after the main archive. They contain references to events, persons, and documents that the main archive establishes in their own time. Some of them comment on the mechanisms by which the archive operates and would substantially reduce the experience of first reading if encountered earlier.
Some of these materials are also, in the technical sense recognized by the relevant authorities, dangerous to a small fraction of their readers. I have included them anyway, for reasons given elsewhere.
— W. Han, archivist.