The rating means that "every possible effort should be made to raise funds to retain it in the country."

The rating means that the system has the resources to provide a good basic education.

"This rating means what it has always meant," he said.

Their commercial paper is popular among money market funds, and the lower ratings mean they are likely to raise interest rates to attract investors.

A rating of one means a country and its airlines meet or exceed the international standards.

What do these ratings mean for the viewer and how are they decided?

"An outperform rating means we expect the stock to beat the market, but not by more than 20 percent," he said.

A slightly lower rating wouldn't necessarily mean a significant difference at all.

"Just because something gets higher ratings doesn't mean it's an event of significant viewer interest."

This rating means a movie has been banned from a part of Australia.