Malory scholar Eugène Vinaver famously argued that the book often called "Le Morte Darthur" is more properly understood to be a collection of eight romances. The eight romances, according to Vinaver, are The Book of Arthur, the Book of Arthur and Lucius Emperor of Rome, the Book of Launcelot, the Book of Gareth, the Book of Tristram, the Book of the Sankgreal, the Book of Launcelot and Guinevere, and the Death of Arthur. For centuries the oldest copy of Malory anyone knew was the print edition, edited and printed by early English publisher William Caxton. Then an assistant master named Walter Oakeshott found a manuscript (that is, hand-written by scribes) in the Winchester library. Vinaver based his theory of eight romances on the fact that the Winchester manuscript was different from Caxton's edition, and especially is organized differently, plausibly like it's eight separate romances in one volume.

A cool thing about the Winchester manuscript is that through the whole thing all the character's names are written in red. This would have been very tedious to do, but it works kind of like an index. You can glance at a page and see right away if this is a Launcelot story.

That image, by the way, links to a site where you can find a digital facsimile of the entire Winchester manuscript. You can click and see a digital picture of every single page!

Anyway, these rubrications are like a search function. You want to read about Lancelot fighting Gawain? Look for their two names together. Bam. You found your place. And this tells us something about how the manuscript was expected to be read! Le Morte Darthur is too long to read in a sitting anyway, but the rubrications show us that it wasn't expected to be read (only) cover-to-cover. Whoever commissioned the manuscript wanted a way to more easily flip to their favourite parts.