Distinctions between the main bodies of texts and all their peripheral detail - indices, heading, prefaces, dedications, appendices, illustrations, references, notes, and diagrams - have all long been integral to orthodox conceptions of nonfiction books and articles.
Authored, authorized, and authoritative, a piece of writing is its own mainstream. Its asides are backwaters which might have been - and often are - compiled by anonymous editors, secretaries, copyists, and clerks, and while they may well be providing crucial support for a text which they also connect to other sources, resources, and leads, they are also sidelined and downplayed.
