Already posted this in the Steam discussions, but posting it here in case others are wondering the same thing

It uses the SendKeys function in the .NET Framework, and the full list can be found here: https://msdn.microsoft.com/en-us/library/system.windows.forms.sendkeys(v=vs.110).aspx

Alternatively, if you just type BFS.Input. and then double-click "SendKeys" in the list that pops up, a new window will open where you can enter whatever you like and it will convert it to the right code in the script