++++ 1 . Preliminary questions - Jurisdiction of the Court - Extension of the subject-matter of the question submitted for a preliminary ruling in disregard of the jurisdiction of the national court - Not permissible ( EEC Treaty, Art . 177 ) 2 . Competition - Agreements, decisions and concerted practices - Dominant position - Effect on trade between Member States - Condition for the application of Community rules ( EEC Treaty, Arts 85 and 86 ) 3 . Competition - Dominant position - Concept ( EEC Treaty, Art . 86 ) 4 . Competition - Dominant position - Relevant market - Determination - Supply of telephone installations by authorized undertakings under a State monopoly - Domestic market ( EEC Treaty, Art . 86 ) 5 . Competition - Dominant position - Existence - Large market share - Insufficient evidence ( EEC Treaty, Art . 86 )