In the WFTDA rules, the lead jammer is the first jammer who legally breaks through the pack, and she retains
the lead jammer status regardless of her position relative to the opposing jammer throughout the jam. In an
OSDA bout, the lead jammer status changes continuously throughout the jam, depending on which jammer is
ahead of the other.
Anita Priest giving Bangarang a whip at Rocky Horror
Photo: James Bennett
Really great article about OSDA :)