it is different in every associations, but if you want an example, the IBF ; you can become no.1 challenger (which make you automatically mandatory challenger), if two of the top five boxers fight each others....for the IBF, the number 1 and 2 spots are open, so you have to be ranked from 3rd to 7th...If you are 4th by example, you need to fight the 3rd, 5th, 6th, or 7th, if you want to become the mandatory challenger, if ALL tohse boxers, are unavailable, injured, already in for a fight, you can go to the 8th, then the 9th, etc. but one of the two boxers HAS to be a top five, and the other at least a top 15...in the top of that, hte IBF president has to approve that fight and of cours you must pay the IBF a fee, does it awnser your question ? for the other organisations (WBC, WBA, WBO), I don't konw the exacts rules, but they are comparable...
What godpepsi said but leaving out the part where you need to pay your sanctioning fees. It's basically extortion.
oh yeah I forgot, sometimes the ogranisation ordonates a eliminatory fight, most of the times, it is two of the top three, because the organisation wants to show they don't give mandatory spots to anybody....they do that once in a century so nobody notices.....so they still look idiots when a top 3 fight a no.13 for a mandatory spot....
I agree about the extortion part...lol, I just wanted to be a minimun gentle for the Organisations.....a minimum....
