premise:  Interest on delinquent taxes and other receivables that arise as a result of custodial operations (582) Interest on post-1991 direct loans (582) Interest on Treasury securities held by revolving funds (590) Interest on Treasury securities held by trust funds and special funds except trust revolving funds (587) Interest on Treasury securities held by trust revolving funds (591) Interest on uninvested funds held by direct loan and guaranteed loan financing accounts (591) Interest received by one fund from another (588) Interest received by Treasury (591) Intragovernmental sales of goods and services by a fund other than a revolving fund (589) Intragovernmental sales of goods and services by a revolving fund (589) Negative subsidies on post-1991 direct laons and loan guarantees (598) Penalties due to delinquent taxes in connection with custodial activity (578) Premiums for SMI (Supplementary Medical Insurance), bank deposit insurance, pension benefit
hypothesis: SMI is a shortened word for "Supplementary Medical Insurance".