violation or nonobservance of established rules and practices, deviation from or violation of a rule, law or principle, irregularities - things which are not done in the correct way and which are possibly illegal, any infringement of a provision of Community law, in the fields referred to in Article 1 (1) of that Regulation, that is the result of an act or omission by an economic operator which is harmful to or may be harmful to the EAGGF Guarantee Section