Documentary Credit、Clean Credi、Irrevocable L/C等都是貿(mào)易往來中所會涉及的信用證種類，而Irrevocable L/C所對應(yīng)的是Revocable L/C，對比分析可知，前者所具有的實用性要高于后者，因此在外貿(mào)往來過程之中，使用后者所具有的效果更為顯著一些，能夠讓貿(mào)易方的收益得到保障。
Irrevocable L/C所指的是什么呢?它所指的是交易雙方指定某銀行開出信用證之后，只要這一信用證處于有效期之內(nèi)，如果沒有獲得相關(guān)當(dāng)事人的認(rèn)可，那么開出這一信用證的銀行就不能夠?qū)ζ溥M(jìn)行撤回，或者是對相關(guān)內(nèi)容進(jìn)行修改，只要交易方中的受益人所提供的相應(yīng)單據(jù)符合其規(guī)定，該銀行就要履行其應(yīng)具有的責(zé)任。在歐美國家一般對其解釋為“It means that the issuing bank can not amend or cancel the credit unilaterally without the consent of the beneficiary and the parties concerned within the validity period of the letter of credit once it has been issued. As long as the documents provided by the beneficiary meet the requirements of the letter of credit, the issuing bank must fulfil its payment obligations.”。在對外商貿(mào)往來過程之中，應(yīng)該在相關(guān)的溝通之中對于信用證使用類型提出需求，一般而言都應(yīng)選擇對自己這一方最有利的類型，例如對于銷售方而言Irrevocable L/C就是很適合使用的一種信用證類型。因此在信用證流程圖中對其一定要加深了解。
例：
Mr. Gibson
We are glad that you are interested in the decorative paintings produced by our company. According to your order list, we need 1000 abstract decorative paintings in the living room, 500 Nordic bedroom decorative paintings and 450 modern abstract decorative paintings in the living room. The price of decorative paintings is so high that we communicated before. We have no objection to the price. A 3% discount will be given.
You mentioned the use of revocable letters of credit in the course of trade, but because of the management requirements of our company in the course of business, it is stipulated that irrevocable letters of credit should be used in the course of the corresponding transactions, so it is unacceptable under the system for such letters of credit as you use, and we hope you will be able to do so at 10. The L/C will be converted into an irrevocable L/C by 30 January, and we will arrange shipment before 2 January after receipt of the L/C. At present, the company has sufficient supplies. We can arrange shipment at any time according to your actual needs. The transportation cost and insurance cost will be borne by you during the transaction. Because of the large quantity of decorative paintings sold this time, the style of the paintings can not be guaranteed to be consistent, and the final interpretation is at our disposal.
吉普森先生
很高興貴公司對我公司所生產(chǎn)的裝飾畫感興趣，根據(jù)貴方所給出的訂貨清單，需要1000幅客廳抽象裝飾畫，500幅北歐臥室裝飾畫以及450幅現(xiàn)代抽象客廳裝飾畫，裝飾畫價格如此前我們所溝通的貴，公司對于價格沒有異議，我公司將給予3%的優(yōu)惠。
貴公司提及在貿(mào)易過程中將使用可撤銷信用證，不過由于我公司在經(jīng)營過程之中所具有的管理需求，規(guī)定在相應(yīng)交易過程中都需使用不可撤銷信用證，所以對于貴方所使用的這種信用證方式根據(jù)制度無法接受，希望貴方能夠在10月30日之前將信用證轉(zhuǎn)換為不可撤銷信用證，我方會在接到信用證之后在1月2日之前安排發(fā)貨，目前公司貨源充足，根據(jù)貴方的實際需求我方可隨時安排發(fā)貨。本次交易過程之中相關(guān)運(yùn)輸費用以及保險費用由貴方承擔(dān)。此次所銷售的裝飾畫由于數(shù)量較多，所以畫品方面的樣式無法保證一致性，最終解釋權(quán)由我方所有。
如上案例回函之中，銷售方重點提及了產(chǎn)品的樣式，尤為重要的是提到了“You mentioned the use of revocable letters of credit in the course of trade, but because of the management requirements of our company in the course of business, the use of irrevocable letters of credit is required in the course of the corresponding transactions, so this form of letter of credit used by you is not acceptable under the system.” 在這其中重點指出了在交易過程中所收取的信用證必須是不可撤銷信用證，在這方面沒有任何協(xié)商的余地，由于該公司產(chǎn)品銷售數(shù)量較多，而且受到了眾多用戶的關(guān)注，所以產(chǎn)品一向是供不應(yīng)求的直接指出“We hope you will convert the L / C to irrevocable L / C by October 30th.”這一點指出了需求對方提供信用證的時間，如果超出這一時間，很有可能無法達(dá)成這筆交易。
當(dāng)然在如上案例之中，前一部分是可以直接借鑒模仿的，不論在任何貿(mào)易領(lǐng)域中都同樣適用，而對于模板的后一部分則不可以完全借鑒模仿，由于在外貿(mào)交易過程之中誰掌控了話語權(quán)，誰在整個交易過程中就能夠主導(dǎo)交易，掌握話語權(quán)則是看其所生產(chǎn)的產(chǎn)品是否是熱銷產(chǎn)品，如果銷售方處于主導(dǎo)地位，產(chǎn)品熱銷，就可以按照如上的模板提出信用證的需求，不過在實際的交易過程中，如果買方處于主導(dǎo)地位，那么賣方在相應(yīng)交易證問題提出方面就應(yīng)該含蓄一些，不能夠照搬如上模板的后半部分，否則很有可能導(dǎo)致這筆交易失敗。
