(i) In general.
A pledged fund is any amount that is directly or indirectly pledged to pay principal or interest on the issue. A pledge need not be cast in any particular form but, in substance, must provide reasonable assurance that the amount will be available to pay principal or interest on the issue, even if the issuer encounters financial difficulties. A pledge to a guarantor of an issue is an indirect pledge to secure payment of principal or interest on the issue. A pledge of more than 50 percent of the outstanding stock of a corporation that is a conduit borrower of the issue is not treated as a pledge for this purpose, unless the corporation is formed or availed of to avoid the creation of replacement proceeds.
(ii) Negative pledges.
An amount is treated as pledged to pay principal or interest on an issue if it is held under an agreement to maintain the amount at a particular level for the direct or indirect benefit of the bondholders or a guarantor of the bonds. An amount is not treated as pledged under this paragraph (c)(3)(ii), however, if --
(A) The issuer or a substantial beneficiary may grant rights in the amount that are superior to the rights of the bondholders or the guarantor; or
(B) The amount does not exceed reasonable needs for which it is maintained, the required level is tested no more frequently than every 6 months, and the amount may be spent without any substantial restriction other than a requirement to replenish the amount by the next testing date.