A string value that specifies the SKU selection fields.
Remarks
When the SKUSelectionFields property is not set to a value in either the SitePages.config file or a control itself, it will first check to see if the relative Item Model has a valid SKUSelectionFields property, and if so, use it. If none is found on the relative Item Model, then the Default SKU Selection Fields value for the Site is checked, and if present, is used.
