From the Definition of Major Violation: Multiple Minor Violations within a Match or Tournament may escalate to a Major Violation at the Head Referee’s discretion or as specified in a rule. Minor Violations carry over into Finals Matches unless otherwise specified within a rule.
I think that generally we would think that the third minor makes it a major. But a number would help with consistency.
GG12 Appendix D Notes: 2. If a Team receives three Minor Violations within the same event, all future GG12 Violations at that event will be considered Major Violations and Disqualifications.
Would the Third count as the Major Violation, or the Fourth? Is it only minor violations of GG12 that count here?