1. A method of distributing data for use in an electronic catalog, comprising: receiving product data for products according to a data model, the data model having one or more classes, each one of the one or more classes being defined by one or more categories, each of the one or more categories being defined by an attribute group having one or more product attributes; and storing the product data in a product data file, the product data in the product data file including both a manufacturer SKU that uniquely identifies a product, and at least one customer SKU that uniquely identifies a product for a customer requesting distribution of specified product data from the product data file for use in an electronic catalog, the manufacturer SKU being associated with at least one customer SKU, the customer SKU also being associated with the customer for which the product data is being stored for subsequent distribution to the customer, wherein the stored product data is suitable for use by the customer in an electronic catalog, the customer being a manufacturer, retailer, or distributor of the products.