18‘Economic activity’ is defined in Article 4(2) of the Sixth Directive as including all activities of producers, traders and persons supplying services, inter alia the exploitation of tangible or intangible property for the purpose of obtaining income therefrom on a continuing basis (Régie dauphinoise, paragraph 15, and T-Mobile Austria and Others, paragraph 33). The latter criteria, relating to the permanent nature of the activity and the income which is obtained from it, have been treated by the case-law as applying not only to the exploitation of property, but to all of the activities referred to in Article 4(2) of the Sixth Directive. An activity is thus, generally, categorised as economic where it is permanent and is carried out in return for remuneration which is received by the person carrying out the activity (see to that effect, Commission v Netherlands, paragraphs 9 and 15).