Which bonds are not secured by the government's tax power but rather by specific project revenues?

Revenue bonds are instruments that are backed specifically by the income generated from a particular project or revenue source, rather than by the taxing authority of the government. This means that they are typically issued by municipalities to finance projects like toll roads, bridges, or public utilities, where the revenue generated from the project will be used to pay back the bondholders.

The security for revenue bonds relies on the revenue streams associated with these projects, which can provide a stable source of income. For investors, this means that the risk is contingent upon the project's ability to generate revenue. Therefore, these bonds do not rely on the general taxing power of the issuer or government but rather on dedicated revenue sources, making them distinctive within the municipal bond category.

In comparison, general obligation bonds are backed by the full faith and credit of the issuing government and are supported by the government’s ability to levy taxes. Convertible bonds and debenture bonds operate under different mechanisms altogether, primarily related to corporate financing and equity conversion options rather than specific project revenues.