<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by LAX UA 1K:
I think the world standard is 7kg/15lbs per carryon with one allowed for economy and two for business/first.</font>
From my experience there's no such thing as a world standard for carry-on baggage.
There's BA which allows only one piece with a total weight of 6 kg(!) for passengers in Y, there's AF which allows a total of 12 kg for all passengers, no matter which class they're travelling in. LX allows up to 10 kg per piece, LH allows 8 kg per piece etc.
andy