The code works like this: the Fox that runs first bumps its SYS(2015) counter a little to make it run ahead of system time and then it puts a SYS(2015) value into the clipboard. The second Fox retrieves this value and spins in a loop calling SYS(2015) until the return value matches the value generated by the other Fox.

The reason for the bumping in the first Fox is to give you ample time to switch from one Fox to another; the reason for the 'out-of-order' pasting of the snippets should be obvious. ;-)

With "IPC" I meant inter-process communication.