Where do government enterprises, like the U.S. Postal Service and local transit agencies, appear in the GDP accounts?

Government Enterprises
In the GDP accounts, government agencies that cover a substantial proportion of their operating expenses by selling goods and services to the public and that maintain their own separate accounts are classified as government enterprises. Government enterprises include agencies such as the U.S. Postal Service and local transit authorities. Because government enterprises are businesses, their value added is recorded in the business sector. However, their operating surplus (or deficit) is recorded as a receipt in the government receipts and expenditures account. For more information please see MP-5: Government Transactions.