USD/CAD and major currencies naming conventions

The Symbol for Trading Aussie against USD is AUD/USD
Similarly for EUR and GBP is EUR/USD and GBP/USD respectively.

Why is that for Canadian, the quoted symbol is USD/CAD i.e. USD comes before CAD?

How does the market decide on this on convention of which symbol should come first?

Anyone?? or is the question too basic/silly?

Maybe basic, but certainly not silly.

The original order was apparently based on relative currency values. That's no longer the case. Probably a good thing, considering the frequency and ease with which AUD, USD, CAD and CHF cross above and below 1 against one another these days.

http://en.wikipedia.org/wiki/Currenc...#Base_currency

So I guess my research tells me that this is just how the convention has been.

And doesn't necessarily depend on importance or AMount of Trade.

I do wonder though, if it'll ever be CAD/USD