Top of page two, this tread, Wiz.
What other indications are you looking for from a Class C cargo hold? Smoke?
The holds are sealed and pressurized but have no fresh air circulation.
You have no way of knowing if the indication is correct or not. It is as simple as that. Remember EK over Chennai?
What will
you do if you get a cargo fire indication in the air. Just ignore it? As NSEU says, false cargo fire warnings on the 777 will only make the decision harder.
That the system is prone to false warnings does in no way mean the warning can't be real.