What's the blue clip do on the ultra flow water ho

I can't find any mention of what the top blue clip on the ultra flow water inlet plug is for. It isn't mentioned on the instructions though it is there on the pictures. It won't hold the hose in place when you refill the water carrier. What purpose does it serve? It's a question I ask every time I fill up the water container then forget about for till the next time we run out.