Wow, lots to think about!
The maintainer suits as described in the book of D'ni are an example. In the book, there are special small linking books that fit in "nova resistant" maintainer suits. Atrus specifically writes a linking book into an unknown age for those suits.
I'd be more comfortable attributing that scenario from the BoD to a Wingrovism (like the statement in BoA that you need knowledge of an Age's descriptive book to write a linking book from it back to d'ni...huh?). Since whatever book the maintainers use to link to the unknown Age stays behind anyway, it doesn't need any special timing mechanism or be especially compact. (Besides, since Maintainers were the first to link to an Age, and all other sources say that the first link is made through the descriptive book, and descriptive books were in general rather large, it seems ridiculous that Maintainer Suits would require outbound linking books to be small.) The book that needs to fit the timed mechanism is the one leading back to d'ni, and Atrus&co. could easily have used maintainer stock for that.
Another example is if you want to make a prison age, don't want to use the descriptive book for the trap, but also don't want to risk leaving a linking book back.
(Yes, burning the linking book while linking back is an option, but it doesn't meet my security standards.)
The alternate linking book writing method
would be convenient for writing multiple links to prison Ages, but it's easily worked around by burning a linking book on your way out. (That seems amply secure to me: how would you unburn a linking book? Cyan's also claimed that burning books was the usual method of destroying them, so it must've been secure for them too.) I don't consider this point especially weighty in deciding whether or not to disrupt canon.
Otherwise there is still the matter of linking to an age that does not have a descriptive book. If a linking book syncs to an age itself, without any sort of reference to a descriptive book, it wouldn't make sense for the linking book to shift along with some unrelated descriptive book that happened to link to the same age, but now has shifted the link. However, that would make sense if there were books that did sync to the descriptive book. As some sort of safety it would make sense to have both options available.
Writing the linking book in the Age (without explicitly referencing the descriptive book) doesn't mean that the book isn't tied to the descriptive book in some way, or that the links shouldn't shift together. Remember that the link from any book is actually "shifting" all the time as the Age evolves: even a flickering fluorescent lightbulb is enough to split an Age into instances, and the fact that in all the combined experience of the d'ni, linking books always continue to agree with descriptive books means that they must be tied together in some way. Naturally, this raises the question (as you have) of how a linking book shifts to match a descriptive book to which it has no explicit reference. The answer is a little counterintuitive, but it makes sense: Suppose you're in an Age, and you write a linking book (to that Age). Now I link in from d'ni, and at that moment, I can be sure that the link I used leads to the same Age instance as the link you just wrote, since we are both here and can wave to each other.
Now I'd like to put the two books side-by-side and check each day that they lead to the same instance. To do that, I'll need to bring your book back to d'ni, but that's possible since there's a linking book here linking to d'ni. (Can you see where I'm going with this?) That linking book must have been brought here through another linking book to this Age - when I leave using it, your linking book is now can now be considered tied to the instance linked to by that linking book (and, through it, to the original descriptive book). (Note that there are actually other ways of comparing your new linking book to an old one, e.g. I could have brought another linking book to this Age with me, and then after writing a new descriptive book we could carry them both to a third Age and compare them that way, but the end result is always the same: consistent histories is a theorem of quantum mechanics, and this carries over to the many-worlds interpretation.) Reading back over this, it doesn't sound too clear, so I'll summarize: linking books to an Age being tied to that Age's descriptive book is a
consequence of linking theory, not an assumption.
It would also facilitate an IC explanation of different versions of ages, or instancing:
e.g. someone distributed Age Synched linking books, but later updated the descriptive book. In this case it makes sense that some people still have "old" books, and link to the old age, while others have new Age Synched books.
If the linking books were (always) Descriptive Book Synched, every book would automatically update to the new version.
It would also be a safety if some were able to write both Age Synched books and Descriptive Book Synched books while writing. If someone accidentally forgot something (or someone!) after changing the descriptive book, an Age Synced book would make it possible to retrieve the object or person. A simultaneously available Descriptive Book Synched linking book would help to make sure you can always go to the most recent version.
(After all, we're all experimenting with the art, so we don't have the same "write once, change never" attitude as the D'ni did.
These are good points, but there are two separate issues here: instancing and age updates - I'll talk about them separately.
Instancing: My personal preference is toward as little IC instancing as possible, for a few reasons: In a story sense, instancing has always been attributed to Yeesha and was presumably implemented through bahro methods (which we're incidentally trying to avoid); the d'ni never had instances and they managed.
In a gameplay sense, my preference would be for there to be many distinct areas, each with a single (IC) instance, so that people can agree to meet here or there without bothering with invitations and sharing. In a linking theory sense, instances are awful: there's no way to determine which changes are propagated through instances and which instance are sources of change propagations and... it's a mess.
OOC instances I don't have a problem with. (E.g. people's default personal areas will probably all be OOC instances of each other, modulo some minor customizations. Like Bevin.) Apart from that, I'd much rather that every IC case of "This Age is an instance of that one" be attributed to "These two Ages have different descriptive books with identical text." Which brings me to...
Age updates: As you point out, and I hadn't thought of before, people may wish to keep links to old versions of their Age instances even as others wish to update their Age versions. I'd say that each update should be classified as one of three types. Either:
- Everyone must update the Age. For example, the author wants all Age instances to have a volcano erupt as part of the Age's story.
- The update is optional or randomized, but is a small change. For example, the author implements a subtle change to the Age's weather patterns that is conceivably attributable to natural forcing in the Age's environment.
- The update radically changes the Age in a way that no (probable) natural phenomenon would entail, but people may wish to keep links to old versions. For example, the landscape is abruptly changed and structures are relocated.
Each of the three cases can be handled in multiple ways, even assuming that instances arise from duplicate descriptive books. Respectively:
- This update could be due either to a natural result of the Age's initial conditions, seen or unforeseen by the author, or to the author mass-editing the stock of descriptive books. Which one is the actual cause depends on the storyline.
- This could be due to natural variation in the different instances, or to people requesting that their instances' descriptive books be individually updated with a demonstrated change.
- This could either be a case of the Ages' descriptive books being updated as in the previous case, or it may be that the author merely wrote new descriptive books and changed the nexus entry to the new version. In either case, you could request to keep your old instance and get a new one.
Since it's that last one that's the most interesting, I'll expand with an example. Suppose Andy has mass-produced a bunch of Nighttime Camp Bravo descriptive books and distributed linking books to them as a way of simulating instances. Now he wants to make the radical change to Daytime Camp Bravo. He can do this in one of at least two ways:
- First, announce to everyone that he has a new version of the Age coming out.
- Those who don't want the update (or want both versions at once) should contact him and say so.
- Everyone else gets their corresponding descriptive book altered to the new version.
- Those who wanted both Age versions get a brand-new, already-updated instance. The instance they already have is left unchanged.
OR:
- Andy mass-produces a whole new range of Daytime Camp Bravo descriptive books, one for every currently existing instance of Nighttime Camp Bravo.
- In the nexus, he replaces every linking book to a Nighttime Camp Bravo descriptive book with a corresponding linking book to Daytime Camp Bravo, relabeling it if desired.
- Those who want to keep a link to the old version (or left belongings there) tell him so. He adds those books back to the nexus, allowing those people access to both versions.
The result is that even under the strictest interpretation of canon, there's still room for people to maintain links to different versions of Ages.
