Or 'avis' in French, is not a legally binding act. It can, for example, be a statement from the EU Parliament in the consultation procedure, an internal working document in a committee, a statement from the Committee of the Regions or the Economic and Social Committee.
It can also be, for example, an EU Commission statement on the conditions for EU enlargement necessary to start formal negotiations or a statement of the Court of Justice or Court of Auditors or the European Central Bank.
Notes
The future
The EU Constitution proposes to keep the 'avis' or opinion as one of the EU’s decision-making instruments.