If I'm not mistaken, USBC REQUIRES a/the serial number. AND, if the ball has been resurfaced or damaged it where the number is illegible, must be engraved in full or the ball isn't legal for USBC competion.
Cut and paste below from page 6;http://usbcongress.http.internapcdn....s/ESManual.pdf
BOWL.com | 6
Last updated on 11/16
Ball Manufacturing Specifications
1. Each ball must be uniquely identifiable by the following:
Individual serial number
USBC star logo (As of March 1, 2006) Figure 3a