Here is how to define the property to allow serial (AND) canals as it defaults to false:
<property name="Control All Canals Between Territories To Pass" value="true" editable="false"
Just to be clear... and follow up on this old discussion (without reading it all again).
Is "Control All Canals Between Territories To Pass" implemented in TripleA now?
And the setting will affect all canals on the map, right?
What about if the map maker wants some single canals to be accessible when owning only one territory (only one of the canal's two banks), and other canals requiring ownership of two banks. Like if access through a large strait is possible if at least one territory is friendly and allows pass through canals, but not if both are hostile. Is this possible to code in the XML?
Sadly not. Aside from being not very easy to understand, the only limit of the current system (as I said) is that you can have either parallel or serial canals, not both.
However, if your maker case is that simple, you just need having the default, plus making 2 canals for the first case, each one related to only 1 of the two territories, and 1 canal only for the second case, related to both territories.
The serial canal is needed only if you have serial canals that do not work all exactly the same way (because, if they do, you can just substitute them all with 1 single canal related to all territories).
For example, if you would have the Dardanelles and the Bosporus as serial canals, related to different territories, and you can pass through each one having only 1 of the 2 territories, but you need to be able to pass through both canals at the same time to make through the Turkish straits (there is no Marmara sea zone), this would be currently not possible to enforce in a straight way, but you could get around doing it by having a number of canals (with the default OR inter canals) each one related to territories representing the whole set of possible combinations that would allow you to pass (so, you are not really creating actual real canals, but the final result is the same).
This is why I said that having the possibility of setting the number of territories required for the same canal (that was the initial Veqryn suggestion, and would have created a truly universal system, covering all possible cases, as I demonstrated), instead of always needing all of them (as it works currently, and always worked) would have been a better and actually universal system. However, this property at least assures that the old system's possibilities are kept, thus the changes have been at least absolutely progressive, making the new system absolutely superior to the old one, while still being imperfect (aside from being weird to code), not fully covering all possible cases (while the simple change from AND to OR inter canals, without a property for having the AND, would have opened some new possibilities at the price of closing other existent, albeit unused, ones).
As I said, only the case of having both parallel canals or canals needing ownerships of only some territories plus (in the same game) serial canals not working all exactly the same way is the only currently not supported case.
The new canal options are definitely an improvement. Already using the new options on Age of Tribes' two Danish straits.
I am not at home now so I can't out test out anything on my work in process map:-/
So I am wondering, if I have have a plain old canal setup with two land territories and two sea zones, can the canal be set to only be dependent on one land territory? As I remember, the two canal attachments of the sea zones have specification of the two land territories that looks like this: "LandTerritory1:LandTerritory2". Is it possible to make the canal dependent on only Land territory 1? Like if it said: "LandTerritory1:LandTerritory1" or just "LandTerritory1"?
If not, I might request this as a feature :) It would make sense that a in some cases there were one of the waterway's side that dominated a canal.
You should just forget about the sea zone vs land territory distinction. It does not matter at all if anything is land or sea and it doesn't matter at all where the needed territories are.
You can use canals to limit movement on sea, limit movement on land, or limit movement between land and sea, it doesn't matter at all.
You can have a canal that allows you to move between 2 land territories (or load from a land territory to a sea zone) if you posses a convoy zone somewhere.
A canal is just something that impedes you going from X to Y unless you own all of a total of territories/zones.
So, yes, you can make it simply dependent on LandTerritory1 only; this is actually already possible in the current release and since ever.
A canal needs exactly two territories to go to and from, like any connections do, but you may be requested to own from 1 to infinite of anything to be able to (a 2 here is as good as whatever other natural number (assuming 0 is not a natural number)).
So, you can have a canal you can go through if you own 1 territory, or if you own all of 2 territories, or if you own all of 3 territories, or if you own all of 4 territories... It does not matter where these territories are and they can be some land and some sea.
Besides, the Panama Canal in WWIIv1 (the first game of TripleA) is a canal having only 1 territory you need to own to pass. It is Panama, but it could have been whatever territory anywhere on the map.
Since you are making a WWII map, I highly suggest you use canals to create air-only connections, meaning connections from a territory X to a territory Y where only air can move directly from X to Y in 1 move only: it does not make any sense whatsoever that an aircraft needs anything more than 1 movement to go from Sicily to Southern Italy, just because there are a few km of water in between.
This topic shows that the current main issue of canals is that the code is very unintuitive and misleading, even for experienced mapmakers. The system itself is already almost universal, if you fully understand it.
Also, a thing that it is oft (read always) overlooked: remember that whatever ships wider than a USS Iowa battleship cannot make it through the Panama canal.
Practically, only ships that are 33 meters wide or less can pass through the Panama canal; which means that the German Bismarck and the Japanese Yamato cannot pass through the Panama canal, while the Italian Littorio can. Also, the American Montana and the Russian Sovetsky Soyuz cannot, as well as the actually commissioned Midway aeroplane carriers.
The way you should enforce this is by having a "Battleship_slim" and a "Battleship_fat" (or whatever), and setting "Control All Canals Between Territories To Pass" to true. Then, making 2 Panama canals, the first one being the normal canal and the second one being a canal related to a hacky territory nobody can own, and excluding all units but the "Battleship_fat". Eventually, you may make the "Battleship_fat" a little stronger than the other one.
Of course, this means that, if you correctly represent the Panama canal, then you can't have parallel canals at all, meaning that you cannot have that strait-like canal requiring the ownership of only one side you wish to have.
This is one (100% realistic must-be (a map in which the Yamato can pass through the Panama canal is not a WWII map)) example why having this as a property is not really making much sense, but it should rather have been an option related to each canal, instead (meaning that it would make the only sense if you could decide if canals are serial or parallel in each case, not only once for all the canals in the entire map).
However, at least having this property is surely much better than the previous bad decision of just getting rid of serial canals, that would have made simply impossible to like correctly represent the Panama canal, or any canals that never allow passage of some units, amongst other things.
Generally speaking, I'm not sure what it is worse between bloody losing the possibility of representing canals never transitable by some units (like the Panama canal, or land restrictions of varying degrees for trains, lorries, etc.) and bloody losing the possibility of representing parallel canals (either multiple canals one beside the other, like in WAW, or a canal you need to control only one side to pass, like a strait that can be extensively mined only if fully controlled). It sucks having to choose, but, with the current engine, you have to.
Of course, you can still make a trigger and condition system that will activate / deactivate canals by testing the situation, but this is quite hacky and definitively much clumsier (and overall dumb, because you would be doing with triggers something that should have been done in the code) than an universal actual canal system, condition or something based, we don't have.
Anyway, I would not reopen this issue just because, since the current active developers don't have much mapmaking experience, I fear (especially based on what I had to see in this topic, and not only here) that, if anything gets changed, we may easily end up with something worse (read more basic) than what we have now, that it is actually not too bad, and much underutilized, as m3tan points out.
Hope this helps, in case you are making an actually realistic WWII game.
To give a clear example, you can say that in World At War the B.Carrier and the B.Transport cannot pass through the Panama canal (100% realistic).
Currently, it is possible to implement this (and it has been for many years), but it is not possible to implement both this and the channel parallel chains (in Pacific). You have to choose one or the other.
I have some ideas about how my map will handle canals, but they are not finalized. Maybe you can help with some difficulties and suggestions. All you have written here is good for reference. I will soon post an "official" map development thread, so plz jump into it when I do I can already say that realism is not the primary concern (but nevertheless still a factor to take into account). It will primarily be gameplay and nation survivability (I dont want any of the playable nations to be in danger of being wiped out in the first couple of rounds. PS: You seem qualified to add some info to the PoS2.xml, is that something you have intentions to do? Maybe short descriptions of canal possibilities? (Though I must admit that I have not close-read that section of PoS2.xml recently.
One of my biggest wish for a WWII map is it having ports (sea zones) represented as circles between the land territory and the sea zone. These circles should then have a canal allowing entering and exiting the port only if you own the bordering land territory.
This is fairly obvious and not that hard to do, and would increase the realism of the map immensely, and being very required also for having a sensible naval production (as you surely know, battleships and carrier take about 2 years to commission).
And I suggest taking a read of all Battleships and Carriers and Cruisers produced, and write down the ports where any were so produced during or immediately before WW2, limiting this ability to those ports only.