(i) General rule for purpose and nonpurpose investments.
For investments that are not otherwise described in this paragraph (d)(2), materially higher means one-eighth of 1 percentage point.
(ii) Refunding escrows and replacement proceeds.
For investments in a refunding escrow or for investments allocable to replacement proceeds, materially higher means one-thousandth of 1 percentage point.
(iii) Program investments.
For program investments that are not described in paragraph (d)(2)(iv) of this section, materially higher means 1 and one-half percentage points.
(iv) Student loans.
For qualified student loans that are program investments, materially higher means 2 percentage points.
(v) Tax-exempt investments.
For investments that are tax-exempt bonds and are not investment property under section 148(b)(3), no yield limitation applies.