It's not once or twice someone has asked me what is Para-Dressage. I'll do my best to tell you in a nutshell what it is. I won't bother you with the details about Finnish system so this is going to be shorter than the Finnish version. I will add some useful links to the end for further information.
If we start with a concept of para sport or disabled sport. These are sports played by people with physical impairment. And when we talk about para sports we usually mean those sports you can see on Paralympics. Para-Dressage is one of them or to be precise Para-Equestrian Dressage.
The Fédération Equestre Internationale (FEI) is the controlling authority for all international events in various equestrian disciplines and Para-Dressage is one of them amongst Dressage, Jumping, Eventing, etc. Para-Dressage, as you can guess from the name, is lot like Dressage with few exceptions. It differs from Dressage in couple of ways.
First of all every athlete has a physical impairment and is classified according to the level of their impairment. FEI has a really thorough Classification Manual and athlete's physical impairment are assessed in order to establish their Classification Profile. Athletes with similar functional ability Profiles are grouped into competition Grades. The Grades range from Grade I for the most severely impaired, to Grade V for the least impaired. And the Grade defines the test athlete rides in competitions. Grade I athletes perform only in walk. Grade II and III tests include walk and trot. Grade IV and V tests are performed in walk, trot and canter. Athletes are permitted to use special equipment when this has been formally documented and approved.
Para-Dressage differs from Dressage slightly on how it's been judged. For example Rider's position and seat are not being scored. Some riders may have severe errors in their position but are still able to ride perfectly. It's all about influencing the horse and that is what the judges are grading in tests.
Para-Dressage athletes follow the general rules, Dressage rules and Para-Equestrian Dressage rules. A lot to remember. And by the way did you know that FEI was one of the first International Federations to govern and regulate a sport for both able-bodied and athletes with impairments?
So there it is. Short introduction to what Para-Dressage is. When time goes by and experiences accumulate my version might be longer of what Para-Dressage truly is.
FEI Para-Dressage page (more detailed information about Para-Dressage, classifications, grades, rules, etc.)
FEI Classification Manual (Quite a large PDF, 59 pages)