Infrastructure Debt Fund rules: tightened eligibility, investment limits, bond issuance conditions and minimum tenor for external borrowings. Rule 2F is amended to require an Infrastructure Debt Fund to be set up as an NBFC under RBI rules, invest only in post commencement infrastructure projects with at least one year of satisfactory commercial operation or toll operate transfer projects as direct lender, and to mobilise funds via rupee or foreign currency bonds (subject to RBI and foreign exchange regulations), zero coupon bonds under rule 8B, or external commercial borrowings. ECBs must meet prescribed tenor and sourcing restrictions. The Fund is prohibited from investing in projects where a specified shareholder or associated enterprise has a substantial interest; 'specified shareholder' is defined by a threshold of voting power.