Rule 18/4 in USBC Rulebook:
Can a bowler use an abrasive on just the track or just a portion of the track on the ball?
No. USBC specifications require that the entire surface of the ball be sanded in a uniform manner. Sanding a ball in any other manner would be a violation of Rule 17a, Item 1. The penalty for a violation of this rule can include disqualification, forfeiture, removal from the league, and or suspension of USBC membership.
Rule 17a Item 1 reads: (Unfair Tactics)
Directly or indirectly tampering with lanes, pins or bowling balls so they no longer meet USBC specifications.