MM = middle man. If large amounts of money are part of a deal (horses, art, selling sponsors, etc), you contact an Op to conduct the transfer. It means everything (info, money) will go to the Op. If all goes well, then the Op will transfer the money on. That's just a basic explanation
Op = operator. Also known as Mods or moderators. Like me
Cha-Nilla is correct on the reasons on name changes though. If you don't have either of those examples, then you'll just have to live with your current names. You can submit a ticket to
www.orbisworlds.com if you wish for a clearer answer