Any designated revenue may by resolution of the board be allocated to the payment of the whole or any portion of the principal or interest or both of any bonds.

The allocation may be for either or both:

Until the payment or retirement of the bonds for the benefit of which an allocation was made, the revenue allocated shall be applied solely to the payment of the obligation specified in the allocating resolution.

An allocation may be made for the exclusive benefit of any one or more issues or portions of issues of bonds of a district designated in the allocating resolutions or in the discretion of its board for the benefit of any bonds of the district at any time issued or outstanding.

Any allocation shall be irrevocable until all of the bonds for which the allocation was made and their appurtenant coupons have been paid or retired.