Yahoo's and Microsoft’s agreement would allow the Sunnyvale, Calif., company to terminate their partnership if it doesn't perform well enough against Google on the key metrics of revenue per search and U.S. market share, according to a termination provisions in a Form 8-K, Yahoo! filed with the Securities and Exchange Commission, but the catch’s that the filing doesn't say precisely how well the Microsoft-driven search partnership would need to perform against Google to justify a termination. The filing refers to measures specified in the deal between the companies, without giving the actual numbers, reported.