here is a description taken from this link:
"Confectioners or powdered sugar - In Britain it is called icing sugar and in France sucre glace. This sugar is granulated sugar ground to a smooth powder and then sifted. It contains about 3% cornstarch to prevent caking. Powdered sugar is ground into three different degrees of fineness. The confectioners sugar available in supermarkets – 10X – is the finest of the three and is used in icings, confections and whipping cream. The other two types of powdered sugar are used by industrial bakers."
I live in Wa. Sate and the powdered sugar I buy in the store says that it is "confectioners powdered" and it contains sugar and cornstarch (to prevent caking)
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