against delivery =against the copy of B/L?

against delivery =against the copy of B/L? 100% against the copy of FIRST PAYMENT 10%T/T,the balance against the copy of the b/l 100% T/T AGAINST THE COPY OF THE B/L WITHIN THROUGH SINOSURE T/T payment against the copy of B/L in one time 30% advanced and balance paid against copy of B/L 和30% advan 英语翻译T/T 30% prepaid,70% paid against copy of B/L T/T after shipment of goods and against receipt copy B/L by delivery documents against payment pay against for delivery 有个客户已合作多年了,一直都使用L/C,这次的单,他想改用:100% TT against copy of the do 请问Payment against delivery是什么意思