While not Taiwan-specific, some uses of the terms DDU and L/T can be found in Transfer of Ownership in International Trade, 2nd Edition (which is also available on Google Books).
DDU is Delivered Duty Unpaid, and in the book, p. 441 on the chapter on Switzerland says
The same principles apply wherever the seller has merely to place the goods at the disposal of the buyer or his agent at an intermediate place, such as the berth at the port of shipment (FAS: Free Alongside Ship) or at destination (DES: Delivered Ex Ship; DEQ: Delivered Ex Quay; DAF: Delivered At Frontier; DDU: Delivered Duty Unpaid; DDP: Delivered Duty Paid). In all such cases, only the actual act of taking delivery of the goods by the buyer (or his agents) as per INCOTERMS 2000 B 4 will trigger a transfer of ownership to the buyer.
And on p. 112 in the chapter on Denmark says
The same situation exists whenever the seller has to place the goods at the disposal of the buyer at an agreed place or destination (DES/DEQ/DAF/DDU/DDP). The seller is protected against the buyer's creditors until the buyer or his employees have collected the goods, but the buyer is protected already by entering into an agreement or by the allocation of the buyer of the goods, cf. above.
L/T is Letter of Trust, and on p. 153 in the chapter on England says
An examination of the bank's proprietary interest in the goods would be incomplete without a mention of the so-called 'trust receipt'. Where the buyer of the goods has been unable to put the issuing bank in funds for the sum of the credit, the only way he can obtain funds with which to satisfy the bank is by selling the goods, and the only way he can do that is by acquiring the documents. Now, the surrender of pledged goods back to the pledgor would normally terminate the pledge, a consequence unlikely to commend itself to an unpaid bank. The device used by the commerical community as a way out of this impasse is known as a 'trust receipt' or 'letter of trust' and its effect is to constitute the buyer a trustee for the benefit of the bank of the documents, goods and proceeds thereof. Where the device is in place, the handing over of the documents of title does not extinguish the pledge. Moreover, should the buyer become insolvent before he has sold the goods, the bank can claim a preferential right over the goods without competing with the general body of creditors; and should insolvency strike after the sale of the goods, the bank has a prior claim on the proceeds. This is not to say that the use of the trust receipt is completely free of risk to the bank. Should the buyer, having sold or pledged the goods to a bona fide third party, fail to account for the proceeds to the bank, the third party's title prevails over that of the bank because the buyer is considered to be the bank's mercantile agent in the sale or pledge and the third party is consequently protected by section 2 of the Factors Act 1889.