Clothing design company Guess, Los Angeles, said Tuesday it has formed a portal allowing more than 900 retailers to order products on the Internet. The 19-year-old company has tapped services from Commerce One Inc. to enable automated purchasing, through the vendor's Commerce One MarketSite Portal Solution. The move is a boost for Commerce One's MarketSite strategy, which depends on a critical mass of large companies to be most efficient. Essentially, Commerce One allows companies to quickly link to a service, rather than build their own trading exchange. Commerce One envisions that large numbers of businesses will maintain current supply chains, and begin new supply-chain relationships through the single, open system.