How does the bond rating system work?
| Highest Quality | Moody’s | Standard & Poor’s |
| High Quality | Aaa | AAA |
| Good Quality | Aa | AA |
| Medium Quality | Baa | BBB |
| Speculative Elements | Ba | BB |
| Speculative | B | B |
| More Speculative | Caa | CCC |
| Highly Speculative | Ca | CC |
| In Default | – | D |
| Not Rated | N | N |