Absolutely correct!

Each class of service (Economy/Business/First) is divided into different fare classes.

First: usually 2-3 fare classes
Business: 3-5 fare classes
Economy: 10-15 fare classes

Unfortunately there is no pattern, but airlines within one alliance (Star Alliance / OneWorld / SkyTeam) often use similar fare classes, e.g. Star Alliance uses:

- F for the most expensive First class tix and A for discounted First class
- C/D/J/Z for business class
- Y for fully flexible / most expensive economy fare

Anyhow you could probably spend hundreds of hours comparing fare classes and wouldnŽt really profit very much. Instead IŽd recommend having a look at the fare classes of the airline you fly most and compare the restrictions/benefits to get a basic idea about how fare classes work.