Chocolate Sheet Cake I

INGREDIENTS

• 2 cups all-purpose flour
• 2 cups white sugar
• 1 teaspoon baking soda
• 1 teaspoon ground cinnamon
• 1/2 teaspoon salt
• 1/2 cup margarine
• 1/2 cup shortening
• 1/4 cup unsweetened cocoa powder
• 1 cup water
• 2 eggs, beaten
• 1/2 cup buttermilk
• 6 tablespoons milk
• 1 teaspoon vanilla extract
• 4 cups sifted confectioners' sugar