1. This Directive shall apply, according to the choice made by Member States, to:

(a) undertakings employing at least 50 employees in any one Member State, or

(b) establishments employing at least 20 employees in any one Member State.

Member States shall determine the method for calculating the thresholds of employees employed.

2. In conformity with the principles and objectives of this Directive, Member States may lay down particular provisions applicable to undertakings or establishments which pursue directly and essentially political, professional organisational, religious, charitable, educational, scientific or artistic aims, as well as aims involving information and the expression of opinions, on condition that, at the date of entry into force of this Directive, provisions of that nature already exist in national legislation.

3. [deleted]