For the purposes of this Directive:
(a) 'system of chartering by rotation` shall mean a system which consists of allocating in a charter exchange requests for transport operations, at previously fixed prices and under conditions made known, from customers on the basis of the order in which vessels become available after unloading. Carriers are asked, in the order of their registration on the rota, to choose in turn a load from those on offer. Those who make no choice nonetheless keep their position in the order;
(b) 'carrier` shall mean an owner or an operator of one or more inland waterway vessels;
(c) 'competent authority` shall mean the authority appointed by the Member State to manage and organize the system of chartering by rotation;
(d) 'serious market disturbance` shall mean the emergence, in the inland waterway transport market, of problems specific to that market likely to cause a serious and potentially persistent excess of supply over demand, thereby posing a serious threat to the financial stability and survival of a large number of inland waterway carriers, unless the short and medium-term forecasts for the market in question indicate substantial and lasting improvements.