[Snow]

Here's a little info on Australian airport codes.

YSSY, YMML etc

Y is the international code for Australia

S or M is for the controling center, there are only two in Australia, either Sydney or Melbourne.

Last two letters are for the airport, SY = Sydney, ML = Melbourne, MB = Moorabbin etc etc

And yes the international pax code for Melbourne is MEL and SYD for Sydney, that's what you'd see on your baggage.