Board Thread:The Panopticon/@comment-1293767-20151029072618/@comment-5918438-20160107214405

I think production blocks are one of the only authoritative sources we can use here as evidence. Putting aside series 9 for now, no "real" two-parters by the usual, intuitive definition have been produced in separate production blocks. Heck, even statements by the BBC are meant to sell the episodes, and marketing something as a grand two-part story rather than as two individual episodes, set apart from each other, just sells better.

So you better understand, I will now make a complete list of NuWho two-parters, by a very simple system. Three rules:
 * 1) The two episodes must follow each other in broadcast order, in the same consecutive run of episodes. In other words, if there's an episode in between, it cannot be a multi-parter even if there is a strong narrative link.
 * 2) The two episodes must have been in the same production block, as well as directed by the same director.
 * 3) The two episodes must have a minimum of one guest actor in common, playing the same character, between them, typically one who does not appear in at least the episode before or after the two-parter. They must appear in a consecutive run—if a three-parter, this character must appear in the subsequent episode; episodes 1 and 3 of a potential three-parter do not count.

Here's what we get: (list in production order)

Series 1
 * Aliens of London/World War Three
 * The Empty Child/The Doctor Dances
 * Bad Wolf/The Parting of the Ways
 * - Rose is in the same production block as AOL/WW3 (it's a conspiracy!), but was not broadcast immediately before them, so it's disqualified on grounds of broadcast order.
 * - Other production blocks, like The End of the World/The Unquiet Dead and Dalek/Father's Day, so not have guest characters in common, and hence are standalone.
 * - While Boom Town is part of a consecutive run with BW/TPOTW, part of the same block and has the same director, it does not have any guest characters in common with the subsequent episode. Jack Harkness is not a guest character; he is part of the principal cast at this point in the series. Mickey Smith does appear in TPOTW, but as stated in the rules, he would need to appear in the consecutive episode, not just episodes 1 and 3.

Series 2
 * The Rise of the Cyberman/The Age of Steel
 * Army of Ghosts/Doomsday
 * The Impossible Planet/The Satan Pit
 * - The Christmas Invasion/New Earth share a director, same production block, and follow each other, but they do not belong to the same run of episodes (christmas special isn't main series) and they do not share a guest character. DT and Billie are not guest actors in the slightest.
 * - Again, you have examples like Tooth and Claw/Girl in the Fireplace, and The Idiot's Lantern/Fear Her, where they're filmed together by the same director, but fail on grounds of broadcast order and a lack of consecutive guest characters.

Series 3
 * Daleks in Manhattan/Evolution of the Daleks
 * Human Nature/The Family of Blood
 * The Sound of Drums/Last of the Time Lords
 * - Quite notably to this discussion, as was the intent of the head writer, Utopia is not part of a three parter with the finale. It's not even the same director as with Boom Town, which also belonged to the same block as the finale. Yes, it shares a guest character, but Utopia and the two-part finale were filmed in different blocks, by different directors (and thank god for that, because Graeme did a fantastic job with Utopia), so we cannot consider those three to be, together, a multi-part story. And now you can see that production intent plays into this. If a story was intended to be a two-parter, it follows the requirements stated above. Otherwise, it's just like applying Doctor-lite to The Crimson Horror.
 * - Smith and Jones/The Shakespeare Code makes two of the rules, but fails immediately on the consecutive guest character requirement.
 * - ''This series, the Christmas special was in its own production block.

Series 4
 * The Sontaran Stratagem/The Poison Sky
 * Silence in the Library/Forest of the Dead
 * The Stolen Earth/Journey's End
 * -''Though it follows on from TSS/TPS and has a guest character from then, The Doctor's Daughter is a standalone because it has a different director, and belongs to its own production block, with Midnight. TDD and Midnight are not a two-parter, of course, because there's an episode in between in production order, and they don't share a guest character.
 * -''Just like in series 1 and 3, there is a penultimate story (and third to last episode) which ends on a cliffhanger that leads to the two-part finale. However, as before, Turn Left is not part of a three-part finale, even though it hits almost every box. Same director, guest character in common and in the same consecutive run of episodes. Why does it not meet the requirements, then? Different production block, which also means different producer. RTD seems to have a thing for penultimate stories followed by a two-part finale.

2009 specials
 * The End of Time parts 1 and 2, if it counts
 * -TEOT aside, all episodes were filmed individually, by different directors. The Waters of Mars sort of has a guest character in common if you count that Ood, and again, ends on a cliffhanger like other penultimate episodes before it, but has a different director to TEOT.

Series 5
 * The Time of Angels/Flesh and Stone
 * The Hungry Earth/Cold Blood
 * The Pandorica Opens/The Big Bang
 * -''Though Victory of the Daleks and The Beast Below were produced in the same block, by the same director, they do not feature any guest characters in common. Also, Victory seems to have been filmed first of the two, yet was broadcast second.

Series 6
 * The Impossible Astronaut/Day of the Moon
 * The Rebel Flesh/The Almost People
 * -''Finally, we can clear this up with this rule. AGMGTW is a standalone mid-series finale, not connected to TRF/TAP because they belonged to different production blocks, and had different directors.
 * -''Let's Kill Hitler is also not together with AGMGTW in a two-parter, because different directors and different blocks. LKH was actually produced in a block with The Wedding of River Song, and of course those two can't be a two-parter because the two do not follow each other in broadcast order, and were also done by different directors within the same block.
 * -Night Terrors and The Doctor's Wife, though same block and same director, do not have a guest character in common, and were also produced out of order (Night Terrors first)

Series 7
 * Moffaaaaaaaaaaaaaaaat
 * -Dinosaurs and Mercy do not have a guest character in common
 * -The Bells of Saint John and The Rings of Akhaten have different directors, and I don't think any guest characters in common
 * -Nightmare in Silver and The Name of the Doctor have different directors, but do have guest characters in common as well as belong to the same production block

2013 specials
 * All standalones
 * -All episodes, including Name even, have different directors, and were produced at different times.

Series 8
 * Dark Water/Death in Heaven
 * -Sigh. Okay, I'm not counting Missy as a guest character in episodes where she appears very briefly, because she probably appears in most episodes, and that simply doesn't count. She does not play a role that actually takes part in the plot of any episodes before the finale, and she is a recurring character which, I don't think counts as guest. Heck, if we included the Great Intelligence in the last series, that might change things. (On a more careful inspection, it would not affect the status of any series 7 episodes)
 * -I think the same applies to Kill the Moon/Mummy on the Orient Express. Danny appears very briefly in both, but he's a recurring character in the series, and not a guest character who plays a major role in those two stories as a whole. But hey, I guess this one's up for discussion, but based on the rules I explained above, not based on any evidence which is solely narrative.

So as you can see, from series 1 all the way until series 6, at the very least, it is very very clear that all two-parters fit my three rules, and no two episodes which also meet those requirements are not obviously two-parters. If it does not fit those rules, but seems to you to be a two-parter, that can perhaps be acknowledged in the story page, if notable (considered by some fans to be the first episode in a three part story[1]), but there's simply nothing to back that up. We need a rule which is clear, which has no exceptions and no room for debate.

Here's how series 9 pans out with my three rules:

Series 9
 * Under the Lake/Before the Flood
 * The Magician's Apprentice/The Witch's Familiar
 * The Girl Who Died/The Woman Who Lived
 * The Zygon Invasion/The Zygon Inversion

And, if we tweak the rules slightly, so that episodes produced alone in single-episode production blocks, with an absolute maximum of one episode in between them, also count under rule 2: That would also require us to view either Clara after her death as a guest character. Or if that's too much of a stretch, to extend the "guest character in common" rule to allow for specific settings in common as well, if they do not appear in both the previous and subsequent stories, and are unique to that two-parter.
 * Heaven Sent/Hell Bent

Do I think that's two too many stretches for one story (or two stories, depending on your interpretation)? A bit. After all, those two changes would not have much impact on previous series, but would be made exclusively for the last two episodes of series 9. Personally, I'm thinking maybe we should wait it out and see if the next series does anything of the sort as well (two episodes publicised as a two parter, with no guest characters in common, and not produced in the same production block).

Under no circumstances would Sleep No More/Face the Raven be considered a two-parter. Yes, they share a director, but they most certainly do not have any guest characters—nor settings—in common between them. So even if we allowed for one episode in between, the status of Sleep No More and Face the Raven would not be affected.
 * Just to be perfectly clear, the production blocks for the final four episodes of series 9 were as follows
 * Face the Raven
 * Heaven Sent
 * Sleep No More
 * Hell Bent

The only reason I'm included to include Heaven Sent/Hell Bent at all is because I recognise the naming scheme which is present in all other series 9 two-parters, so it does seem like the intent.

By this, I mean: Lots of word relations in all of those cases, including the finale(s), and that's notably not present at all with: Which are the only absolutely clear standalones in this series.
 * 1) Under the Lake/Before the Flood
 * 2) The Magician's Apprentice/The Witch's Familiar
 * 3) The Girl Who Died/The Woman Who Lived
 * 4) The Zygon Invasion/The Zygon Inversion
 * 5) Heaven Sent/Hell Bent
 * 1) Sleep No More/Face the Raven


 * -Face the Raven is most certainly not part of a three-parter with Heaven Sent and Hell Bent, because it has a different director. Period.
 * -Yes, I know people seem to be uncomfortable about counting Girl/Woman as a two-parter. Yes, it is somewhat of a different two-parter than most we've encountered in the past. It's certainly the first time we've seen a two-parter whose two episodes were penned by different people. But you can't logically count the finale as a two-parter, but not those two. This series has two examples of really weird two-parters, done in ways very differently from those in previous series. But you have to realise that Moffat and the production team were playing with something new this series. There were no two-parters at all for a while, and now this series mostly consisted of them. And starting this series, or perhaps only this series (only time will tell), some two-parters are, as quoted just above, "wildly different episodes [...] combined to create a two-part adventure".

While I can't tell you why certain decisions were made, whether it was to allow for more writers, etc, it is quite clear, by the rules that I set out at the beginning, by the rules which have underpinned two-parters since they first started, that The Girl Who Died/The Woman Who Lived is a two-parter. It doesn't really matter how particular editors "feel" about this to our actual classification of stories, any more than it matters what individual editors think about "canon". We have T:VALID and four specific rules to go by, and, with my proposition, we might have T:MULTI or T:STORY COUNT, with three clear rules to go by there as well.

The point of any policy is to have something clear and concise to point to, so when somebody asks "is this a two-parter?", we don't need to go into a 3-month-long discussion debating everything we already know. All we say is, yes, it meets all three requirements, or no, it fails that one. I do not think the credited writer is all that significant to "multi-part" designation, because all of it is commissioned by the executive producers. The writers themselves don't decide what gets to be a two-parter. If something is considered to be a two-parter by those in charge of production, it will never fail these three rules. The two (or more) episodes will always:
 * 1) Follow each other directly in broadcast, as a consecutive run, which almost always means 1 week in between each (1 week is not a requirement, but tends to be the case).
 * 2) Belong to the same one (1) production block, with the same one (1) director in charge of all of them. (In an alternative version, if the two episodes are produced individually and alone in their own production blocks, and there is only one singular episode in between them, those two stories might count as well.)
 * 3) Have a minimum of one (1) guest character in common between the two or more episodes, almost always played by the same guest actor. (In an alternative version also proposed to allow for the series 9 finale, a specific setting in common between the episodes is also allowed.)
 * If Clara is accepted as a guest character for the two episodes, that last modification will not be necessary, at least not until and unless next series does something similar.
 * If those two modifications, nor the Clara proposition, are accepted by the community at this time, then Heaven Sent/Hell Bent will not be considered a two-parter by us by currently proposed policy.