An example would be 0EK764S13SEPJNBDXBMM2 this would add a segment for 2 JNBDXB on Sep 13 on the 705PM flight this will book in the S class that Emirates needs. I always try to buy enough ZEDs before I leave home to get me through several different routings. Buying in foreign locations is too iffy. And refund is so easy.