that +? is based on the person's summoning lvl...
since summoning lvl affects ur combat lvl.
so they have xxx+?? if any players with summoning lvls goes to any pvp world or f2p world...
so that xxx is aka. f2p lvl... while that +?? is based on summoning lvl
this is basically due to f2p max cb lvl is 126... and with summoning, it's 18 (f2p max + 12)