In the "creating multiprocessor Nios II systems"tuturial,what is the "ipc"file for?

Hi,

Everyone,

In that tuturial,in the software ,I have found the "ipc"files in both of the CPUs.However ,it seems that we never use ipc in this example.Even there is an inter processor communication,I think that is done through command Q of microC/os ii. In all the files,nothing related to the "ipc"file has been cited or used. I really feel confused why we should have this file.......:confused: Anyone gives me a clue....Thanks:D