what is a transmission tariff
Transmission, Markets, and Services Tariff (ISO Tariff) is known as the Open Access Transmission Tariff (OATT). The OATT: 1  Helps ensure that all transmission owners and transmission customers have fair and open access to transmission service in New England.ransmission, Markets, and Services Tariff (ISO Tariff) is known as the Open Access Transmission Tariff (OATT). The OATT: 1  Helps ensure that all transmission owners and transmission customers have fair and open access to transmission service in New England.