Section 5. Section four does not apply if and to the extent that the applicable gift instrument indicates the donor’s intention that income of an institutional fund shall not be accumulated or shall not be added to the principal of the fund. A restriction against accumulation or addition to principal may not be implied from a designation of a gift as an endowment fund, or from a direction or authorization in the applicable gift instrument to apply to the uses and purposes of the fund the “income”, “interest”, “dividends”, “currently expendable income”, or “rent, issues or profits”, or a direction which contains other words of similar import. This rule of construction applies to gift instruments executed or in effect before or after the effective date of this section.