I've only done some diving in the Mediterranean (south of France). And the orange/yellow colors is the "recommended" advice I got from the local dive shops and

I've only done some diving in the Mediterranean (south of France). And the orange/yellow colors is the "recommended" advice I got from the local dive shops and the common understanding in the diving boats I've been on. It a shame that CMAS, PADI or SSI don't propose a standard.