Like coffee beans, sugar can be ground more coarsely or finely as it is transformed into confectioner's, or powdered, or icing sugar. With sugar, however, coarse is a very relative term; all confectioner's sugar is ground very fine.

Confectioner's sugar can range from 14X (the finest) to 4X or 3X (the coarsest). The number refers to a measure of the fineness of the screen through which the ground sugar can be sifted.

Professional bakers may have access to a variety of textures - they most commonly use 6X. Those of us who are limited to the shelves of a grocery store generally have only 10X available, at least in this country. Here and there you can find 4X in the store (Domino Sugar produces a one pound box of 4X, but it is hard to find).

If your recipe asks for 10XXXX confectioner's sugar, it is a misprint. Use whatever confectioner's sugar you can find, and your frosting will turn out fine (unless the recipe contains other, more troublesome, misprints).