Generally not a real huge part -- I don't want to inhibit the usefulness of the book, or bulk up its size, by adding a lot of "flavor text" that's of marginal usefulness to many readers.
However, we do want to give the book some "color," so here's what we're doing. First, the illustrations will have a dandy little stylized border by Keith Curtis that resembles an UNTIL computer frame, or something like that. Second, where possible, I'm going to include sidebars that accompany each illo. Some will be "excerpts" from the Database itself, but others will be agents' field notes, scientist's notes, and so on.
Should be a lot of fun, and it will include some form of "power ranking" system. It won't be the same as the Alpha-Beta-Delta-Omega system in CKC, though -- that's a Department of Defense method for ranking the overall threat posed by a villain, whereas this is an UNTIL ranking for specific powers.