You might take it for granted that everyone understands eventing and the various levels but not everyone does. Trying to explain it to people isn't the easiest the things either. If you weren't brought up learning to read from eventing schedules instead of 'chip and the magic key' don't worry, just keep reading...
All eventing run by British Eventing or the FEI is called affiliated eventing if it's not run by either of them it's called unaffiliated eventing. The lowest level you can start affiliated eventing at is BE80 which as the name suggests has jumps at about 80cm high and a very simple dressage test. You also get alot of help in these classes as they're designed to introduce people to eventing.
The next step up is BE90 (previously intro) and after that BE100 (previously Pre - Novice) with jumps at 90cm and 1m respectively. At this point you also get BE100plus which has novice (the next level up) dressage and showjumping (although a bit easier) then a BE100 XC track. BE100plus is the highest level a rider can ride at for the first time at BE events although this only applies to the rider so once you've done one you're sorted. That is as long as you're over 17 as if you're younger you get your own special set of qualification restrictions but thats a whole other article....
After the BE100 comes novice with jumps around 1.15m and you start to get things like medium trot in the dressage tests. Moving on from there you get intermediate which has showjumping fences at around 1.25m and bits and pieces like shoulder in in your dressage tests. The XC at intermediate also becomes somewhat meatier and more technical.
The highest national level is advanced with fences at around 1.30m and flying changes in your dressage tests for example.
But thats not it. International competitions have their own set of levels denoted by stars and letters. * is an international novice, ** an international intermediate, *** an international advanced and above that **** ie Badminton, Burghley and Pau for example.
There are also 2 types of international competition. A one day international (which normally has day before dressage so lasts 2 days - typical) is a CIC. Whereas an international 3 day event is a CCI. So an international intermediate 3 day event would be a CCI** and a one day international advanced would be a CIC***.
While we're on funny letters, if you ever look in the FEI rule book or on eventing ireland you'll see something like this "CNC* or CNC**" all it means is that it's a national class. So a CNC** is just an intermediate and a CNC*** is just an advanced class.
There you go, looks simple now. Trouble is it takes a while to get up to the higher grades... If you're reading this chances are you weren't brought up on eventing and want to get cracking. I sympathies and if you want to follow my attempts to turn professional and move up the grades check out my website - www.olilawrence.co.uk As well as that check out one of the best guides on eventing by the Pony Club.