Good to know. Guess the next question would be since the host machine is determining the sexp events does the client need the feature in the code? For example that add-remove-escort sexp priority change. If I have it and the client doesn't will the ships show up in the right order on the client?
I'd be pleasantly surprised if the add-remove-escort SEXP had any effect on client machines even before I fixed it. The SEXP code certainly isn't doing a multi callback so unless the HUD code is passing it on to the clients that there has been an update somewhere I doubt that it does.
Then there is the cap huge beams attacking bombs "feature". If I use the ship-turret-target-order and the client doesn't have a version with that will it cause any problems with the cap ship behavior or is that also all determined on the host side?
In that case you'd almost certainly be fine. The host does all the ai work and then notifies the client that a ship has fired a weapon and at what.
In most of these cases it is possible to take a rough guess if there will be a problem.
1) The commonly used [V] SEXPs can be assumed to be safe for multi. If there was a problem with one of these not working I assume you'd have noticed it already.
2) All conditional SEXPs are safe as they're only evaluated on the host anyway (unless they have a side effect of some sort - Can't think of any which do off the top of my head though).
3) Any change SEXP that touches functions which the host is completely responsible for can be assumed to be safe for multiplayer as the updates will be passed on by the already existing update code. That means stuff like AI functions should almost always work.
4) The Set ammo, Set weapon, end-mission and modify-variable SEXPs all work in multi. I know cause I fixed them. Taylor has fixed a lot of other multiplayer problems but as far as I know I'm the only one fixing SEXPs.
5) Assume any other SEXP that doesn't fit in one of the above mentioned categories won't work until you test it and make sure for certain it does.
Remember that in pretty much any case where this sort of thing happens the host is completely unaware that there is a problem. I've had cases where I've used the change-ship-class SEXP for instance and everything looked fine on the host machine when I changed a ship from a fenris into an orion. The clients however had weapons appearing from nowhere, continued to a fenris and found themselves bumping off an invisible orion shaped object (All collision detection is done on the host. Which is why you can get smacked by apparently non-rotating objects like the Shivan Comm Node or the Knossos portal if you're on a client machine)
