Nothing.
It is an abbreviation for gallon, but the gallon is NOT part of the metric system.
does international system of units mean a version of the metric system used by modern scientists
1 gram is in the metric system. do you mean 1ounce?
millionth
If, by 'metric system', you mean 'SI system', then the base unit for mass is the kilogram
THE METRIC SYSTEM WONDERLAND or THE WONDERS OF THE METRIC SYSTEM
does international system of units mean a version of the metric system used by modern scientists
1 gram is in the metric system. do you mean 1ounce?
it means the numbers in the metric system
It is a measurement of volume using units from the metric system.
millionth
It means multiplying with constants from a non metric system (such as length using yards, feet, inches) to a metric system (using meters)
If, by 'metric system', you mean 'SI system', then the base unit for mass is the kilogram
THE METRIC SYSTEM WONDERLAND or THE WONDERS OF THE METRIC SYSTEM
L means liter in the metric system. Here is the URL to the metric system. http://lamar.colostate.edu/~hillger/common.html
I don't know exactly what you mean; but neither ounces nor gallons are part of the metric system. Look at the Wikipedia article on "SI" to get information about the current, official, version of the metric system.
Metric system
the French use the metric system if that's what you mean