Article I

Belgium is a Federal State made up of communities and regions.

Art. 2

Belgium is made up of three communities: The French Community, the Flemish Community and the German Community.

Art. 3

Belgium is made up of three regions: The Walloon region, the Flemish region and the Brussels region.

Art. 4

Belgium has four linguistic regions: The French-speaking region, the
Dutch-speaking region, the bilingual region of Brussels Capital and the
German-speaking region. Each «commune» (county borough) of the
Kingdom is part of one of these linguistic regions.

The limits of the four linguistic regions can only be changed or modified by a law adopted by majority vote in each linguistic group in each Chamber, on the condition that the majority of the members of each group are gathered together and from the moment that the total of affirmative votes given by the two linguistic groups is equal to at least two-thirds of the votes expressed.

For more see link below

http://www.fed-parl.be/gwuk0001.htm#E11E1