FX has been discussed many many times. You should read back at least one year in each of the general, newbies and recruiter forums if you are researching expediting as a possible career. Doing so will give you many discussion of FX and others to study. Once you've absorbed as much of that as you can you'll have a good foundation to pursue further questions you may have. Good luck.
Leo Bricker, 73's K5LDB, OOIDA 677319
Owner, Panther trucks 5507, 5508, 5509
Highway Watch Participant, Truckerbuddy
EO Forum Moderator
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Support the entire Constitution, not just the parts you like.