集装箱免箱期分为Free Demurrage和Free Detention：

Demurrage一词在法律英语中就是指（船舶）租借逾期费；滞留；滞留费（the delaying of a ship, railway wagon, etc, caused by the charterer's failure to load, unload, etc, before the time of scheduled departure）。Demurrage和Detention都是外贸航运的用语，D&D（Demurrage & Detention）都是滞箱费/滞柜费，指的都是因为货物在目的港滞留而收取的费用种类。

Free Demurrage：从货柜卸到码头开始计算，直到货柜被提出码头为止。

Free Detention：货柜从提出码头开始计算，到空柜返回码头止。

Ree Demurrage Days：货物抵港后集装箱在码头内的免租期。The demurrage period is calculated form thedate of discharge of full container up until the date the full container is clearedout of port, after deducting the standard free time.

Free Detention Days：货物抵港后集装箱拖离，在码头外的免租期。The detention period is calculated from thedate the full container is cleared out of port up until the date the container isreturned empty by the consignee to the carriers stack in port.

Demurrage可缩写为DM，意思是滞期费。超过期限，收货人如仍未提货, 应按船公司规定交Demurrage

Detention可缩写为DT，意思是滞箱费。超所期限，收货人如仍未还空箱, 应按船公司规定交Detention.

免堆期英文为Free Storage：

是指码头允许免费堆存的时间，超过即收取滞港费。集装箱堆存在码头的免堆期；这个时间取决于码头的规定。

Free Demurrage、Free Detention和Free Storage的区别：

Free demurrage和Free detention是由船公司收取的滞柜费，正常是7天左右；

Free Storage则是码头收取的堆存费，一般是在5-7天。

参考双语例句：

In June 2009, the United States International Trade Commission published a report on sales of agricultural products to Cuba in which it was recognized that the constraints on trade between the two countries included: difficult payment terms for Cuban importers; additional costs incurred by Alimport for storage or demurrage owing to bureaucratic obstacles; the complex and drawn-out licensing process for exporters who need to travel to Cuba; travel restrictions affecting Cuban negotiators; and penalties under United States law for foreign ships that have docked in Cuban ports and for the Cuban Government’s purchases from certain countries for geopolitical considerations.

2009年6月，美国国际贸易委员会发表了一份关于向古巴出售农产品的报告，承认限制两国之间贸易的因素包括：古巴进口商支付条件困难；由于Alimport公司的官僚增加了储存或滞港费用；需要前往古巴的出口商获得许可证的程序复杂拖沓；对古巴商人的旅行限制；美国法律对停靠古巴港口的外国船只的惩罚；古巴政府从某些国家的采购是出于地缘政治考虑。

Examples of the matters with which we regularly deal are: cargo claims, bunker disputes, laytime and demurrage disputes, hire and off-hire claims, ship repair claims, performance warranties, commodity disputes, CIF and FOB contracts, trade finance and documentary credits, cargo policies, haulage and freight forwarding contracts; cross-border courier business as well as claims for loss of life / personal injury sustained on board vessels.

此外，我们亦时常处理各种海上货物运输纠纷、燃料纠纷、装卸时间及滞船费纠纷、起租及停租的申索、船舶维修的申索、履约保证、商品纠纷、CIF及FOB合同、贸易融资及跟单信用证、货物保单、拖运或货运代理合同、跨境速递业务以及海上的人身伤亡申索等。