A promise to set aside, dedicate and use exclusively for specified purposes certain categories of property, generally money or other intangibles.
See Also
A covenant that is the opposite of a pledge – a promise not to pledge property, generally money or other intangibles, to any party other than the issuer, a letter of credit provider or other intended beneficiary of the negative pledge.

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Redemption of the bonds in the case of certain unexpected or one-time events occurring with respect to the bonds or the project financed with the proceeds of the bonds.