If the Council has not appointed the members of the arbitration board within one  month of being called upon to do so, they shall be appointed by the Court of Justice  within a further period of one month.

The arbitration board shall elect its own chairman.

The board shall make its award within six months of the date of the Council vote  referred to in the last subparagraph of paragraph 3.

5. The second and third stages may not be extended or curtailed except by a decision  of the Council, acting unanimously on a proposal from the Commission.

6. Nothing in the preceding paragraphs shall cause the transitional period to last  more than 15 years after the entry into force of this Treaty.

7. Save for the exceptions or derogations provided for in this Treaty, the expiry of  the transitional period shall constitute the latest date by which all the rules laid down  must enter into force and all the measures required for establishing the common  market must be implemented.

Article 7a

The Community shall adopt measures with the aim of progressively establishing the  internal market over a period expiring on 31 December 1992, in accordance with the  provisions of this Article and of Articles 7b, 7c, 28, 57( 2 ), 59, 70 ( 1 ), 84, 99, l00a and 100b and without prejudice to the other provisions of this Treaty.

The internal market shall comprise an area without internal frontiers in which the free movement of goods, persons, services and capital is ensured in. accordance with the provisions of this Treaty.

Article 7b

The Commission shall report to the Council before 31 December 1988 and again before 31 December 1990 on the progress made towards achieving the internal market within the time limit fixed in Article 7a.

The Council, acting by a qualified majority on a proposal from the Commission, shall determine the guidelines and conditions necessary to ensure balanced progress in all the sectors concerned.

Article 7c

When drawing up its proposals with a view to achieving the objectives set out in Article 7a, the Commission shall take into account the extent of the effort that certain economies showing differences in development will have to sustain during the period of establishment of the internal market and it may propose appropriate provisions.

If these provisions take the form of derogations, they must be of a temporary nature and must cause the least possible disturbance to the functioning of the common market.

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