This has been the case since the 2008 rules were pubished by ECAHO - if you have a look in the HoCoN catalogue you will see the qualification criteria which is based on entries forward in the class. You can find these also on www.ecaho.org
states the following qualification required for Aachen/Paris:-
Qualification: Horses should have qualified at an ECAHO affiliated show in one of the following ways: • a title of Champion Gold medal or Silver medal winner in a class C Show or a 1st place for yearlings. • a 1st to 3rd place at an A, B, or National Championship Show.
Qualification for A show (e.g. Towerlands)
• 1st to 5th place in an A or B show or • 1st to 5th place in a National Championship Show or • in a C International or C National Show: • 1st place in a class of three horses • 1st and 2nd place in a class of four to five • 1st to 3rd place in a class of six or more horses
Sorry if I'm being thick as well but do you have to qualify every year like in America or once your horse qualified it lasts for a period of time or forever?