Reader cinemazing asks:
When I look at other timelines, specifically a Batman chronological timeline, Batman: Haunted Knight, Long Halloween and Dark Victory are fairly early in continuity as opposed to here. Why is that?
I get asked this a lot, so I'm happy to have a chance to explain. I should start by saying that the "timeline" aspect of the Collected Editions DC Trade Paperback Timeline is actually a misnomer. Most of the time, "timeline" indicates something presented in chronological order, whereas a "reading order" presents books in the best order to read them, regardless of chronology. I would actually argue that the DC TPB Timeline is both a timeline and a reading order, but to say it's more of a reading order might begin to answer your question.
Let's establish first of all what qualifies a book, for me, to go on the DC TPB Timeline. Regular series are a given; when DC Comics publishes an in-continuity Teen Titans series, all the collections of that series will go on the timeline, even if some issues don't specifically cross-over or tie-in with any other books. Ditto if books like Superman/Batman or Legends of the Dark Knight are sometimes in continuity, then all the volumes of that title will go on the timeline even again if some volumes stand on their own.
DC Comics also publishes miniseries, which are sometimes collected. Those miniseries can be, but aren't always, in continuity. If a collected miniseries can be demonstrated to be specifically in continuity, then I would put it on the DC TPB Timeline. If a miniseries tells a story, even one that seems in continuity for the most part, but isn't specifically canonized by a reference from a regular series, then I don't tend to put it on the timeline.
A popular example is Matt Wagner's Batman/Superman/Wonder Woman: Trinity, published post-Crisis on Infinite Earths but before Infinite Crisis, that showed the first meeting between the three heroes. In that post-Crisis continuity, however, Superman and Batman originally met in Man of Steel and then they met Wonder Woman in Legends. The Superman titles at the time upheld that Legends first meeting, as did the post-Zero Hour timeline, and none of the regular series ever referenced the events of Trinity. Therefore, since no regular-series story ever brought Trinity firmly into continuity (and some stories even contradicted it), Trinity is effectively considered an "Elseworlds" and doesn't have a place in the DC TPB Timeline reading order.
Another example is Mark Waid's Kingdom Come, a tale of a troubled DC Universe future, which was indeed first presented as an Elseworlds. That book wouldn't go on the DC TPB Timeline at all, except that a later Justice Society story specifically referenced Kingdom Come, bringing it into continuity even as an Elseworlds. So this is not to say that some Elseworlds don't have a place on the DC TPB Timeline, but rather that any miniseries not specifically connected to a regular series doesn't have a de jure place on the DC TPB Timeline unless it's later referenced by a regular series.
In this way, Batman: Long Halloween and Dark Victory were not immediately assured a place on the DC TPB Timeline (and they were even contradicted by other miniseries and regular-series stories). Once the events of those books were acknowledged by the regular series collections Batman: Face the Face and Batman: Life After Death, then Long Halloween and its related books gained a place on the timeline.
As for how I determined where to place them, let's begin by looking at a non-Batman example. Take these four collections, in the order in which their issues were originally published:
Superman: Man of Steel Vol. 1
Superman: Man of Steel Vol. 2
Superman: Secret Origin
Superman: New Krypton
Technically, Secret Origin is an origin of Superman, so a chronological "timeline" might put Secret Origin next to Man of Steel Vol. 1, Superman's original post-Crisis on Infinite Earths origin.
But this is confusing for a number of reasons. This would have the reader reading two contradictory origins one right after the other, and then going on from Secret Origin to Man of Steel Vol. 2, which equally doesn't match. Secret Origin doesn't enter continuity until after Infinite Crisis, which means a reader would be holding on to aspects of Secret Origin for over twenty years-worth of Superman collections before the events of Secret Origin would come into continuity. And the reader would read a not-yet-in-continuity origin of Metallo in Secret Origin before they read an in-continuity-at-that-point origin of Metallo in Man of Steel Vol. 2, and so on.
Therefore, I think a better "reading order" is keeping Man of Steel Vols. 1 and 2 on the DC TPB Timeline around when they were published after Crisis on Infinite Earths, and putting Secret Origin on the timeline around the time when it enters into continuity, when it's referenced by New Krypton. This gives the reader a non-contradictory reading order, even if it means a little jumping around in Superman's own timeline (you might consider Secret Origin a retroactive continuity "flashback").
For these same reasons, Batman: Long Halloween and its related titles don't appear on the DC TPB Timeline until just before Face the Face because before that point, Long Halloween wasn't specifically in continuity. As a matter of fact, 2000's Robin: Year One contradicts 1999's Dark Victory, and since Robin tied into 2001's Nightwing: On the Razor's Edge before Long Halloween/Dark Victory tied into 2006's Batman: Face the Face, Long Halloween appears on the timeline later than Robin: Year One even though it was published first. To read these books in publication order, the reader would weave in and out of two different continuities instead of reading the books from each continuity with their own related titles.
(Haunted Knight and Catwoman: When in Rome are both pretty well out of continuity, but since they relate to Long Halloween and Dark Victory, I include them on the DC TPB Timeline as one "series" together.)
Thanks again for the question! Best wishes to all and be here next week for new reviews.