STRAIGHT (i.e. consecutive-fiber positioning) is when Fibers 1...n on one end connect in the same order on the other end (1...n). To ensure that transmit goes to receive for each pair, the user crosses patch cables on one end of the link -- on the outside of the patch panel.
1 ----------------------- 1
2 ----------------------- 2
3 ----------------------- 3
4 ----------------------- 4
5 ----------------------- 5
6 ----------------------- 6