There's this command listed in Commands.txt:

Quote :

/out X :only seen by external programs

What does it actually do? Is it the same as /o mentioned in the InSim docs?

InSim.txt:

Quote :

// NOTE: Typing "/o MESSAGE" into LFS will send an IS_MSO with UserType = MSO_O

I've got an InSim watching for /o messages, I just tried /out instead and it didn't trigger anything

It's just a command that doesn't do anything but remains local. It's in the same place that local commands are processed, and does not get sent to the server.

I guess it can be seen in one of the messages that is sent out via InSim so an external program could use it for any purpose.