Thanks LeeG, now I think I understand!.
So, if a remote sensor detects a leak, it communicates with the Floodstop main controller. The main controller closes the water valve, and also triggers the I/O Linc sensor, which is seen by ISY. I think I may be getting this system to monitor my flood danger areas.
I have the ELK M1 also, but the flood detector for the ELK is not wireless as far as I know.
Thanks!