To become a true currency, the SDR would have to be a fully convertible instrument, not a line ofcredit, underwritten by countries with "hard" currencies.
I think a creditinstrument is a written evidence of the extension of a loan.
我认为信用工具就是发放贷款的书面证明。
3
Each negotation must be endorsement on the reverse side of beneficiaries original creditinstrument by the negotiating bank which has to confirm the endorsement on their documentary remittance letter.