在国际贸易中，预付款保函是一种非常常见的贸易工具，用于确保买家能够按时支付预付款。下面是一份国外预付款保函的标准文本，供参考：

TO: [Beneficiary Name]

Dear Sirs,

We, [Name of Issuing Bank], hereby issue this irrevocable standby letter of credit in your favor for an amount not exceeding [Amount in Words] ([Amount in Numbers]) valid until [Expiry Date of the Guarantee].

This standby letter of credit is issued in favor of [Name of Applicant] to secure the payment of their obligations under the [Name of Contract or Agreement] dated [Date of Contract or Agreement].

Any demand for payment under this standby letter of credit must be accompanied by the following documents:

• 1. Signed demand for payment;
• 2. Original standby letter of credit;
• 3. Copy of the contract or agreement between the beneficiary and the applicant;
• 4. Any other documents as required under the terms of the standby letter of credit.

This standby letter of credit shall be governed by the Uniform Customs and Practice for Documentary Credits (UCP 600) issued by the International Chamber of Commerce (ICC) Publication No. 600.

[Name of Issuing Bank] hereby agrees that this standby letter of credit shall be subject to the laws of [Jurisdiction of Issuing Bank].

This standby letter of credit is issued in accordance with the terms and conditions of the agreement between the beneficiary and the applicant.

Yours sincerely,

[Name of Issuing Bank]