The "Canadian" Slicers, normally found on Gen1 and some early Gen2 SHO models, is a non-directional design and can be mounted on either side. The "Italian" Slicers are a directional design and are designed to rotate in one direction, therefore they are designed for "right" and "left" side usage. For Italian rims, you need to make certain you have 2 of each direction. If you look inside the hub area(under the hubcap) you will find notation for each make of wheel. The Italian Slicers will also show the rotation direction on the wheel. Hope this helps.
PS: The Canadian rims originally came with a "blank" hubcap, except on the 91' Plus models. All Italian rims came with the "SHO" logo hub caps. However, many folks have added the SHO caps on to the Canadian rims.