What is a Tie Break in a chess tournament?

TBrk  stands for Tie Break calculations. Often these numbers are not published and only seen by the tournament director so it is reasonable that many players may not have seen them before. These numbers are calculations made by the computer in an effort to put a number a player’s performance and are often used to break ties when two or more players have the same score.
There are probably 20 or more different calculations that could be made. The TD selects the ones in use at the event. The ones shown are the standard ones we use at most of our events where it is not practical to have playoff games.
The first order of tie break is if the players have actually played each other. That solves many ties straight away.
The TBrk C stands for cumulative score and is the first computer calculation we tend to use. It is simply a round by round accumulation of a player’s score. For example if a player wins every game their score after round one will be 1.0, after round 2 it will be 2.0, and so on. The calculation adds the score at the end of each round, ie 1.0 plus 2.0 plus 3.0 plus 4.0 plus 5.0 for a maximum total of 15.
Now let’s look at what happens to two hypothetical players who each score 4.0. One is challenging for the championship. He has won all four games playing on the top board against the top contenders who, like him are unbeaten. Unfortunately he loses the big final match. His running score at the end of each round would look like 1.0, 2.0, 3.0, 4.0, 4.0. If you add them all together you get 14.
The other player loses his first game. This puts him on the other side of the pairings where he will only play people who have already lost a game. Lets say he wins his next 4 games so his round by round score would look like 0.0, 1.0, 2.0, 3.0, 4.0. If you add these numbers together you get 10. This reflects the fact that his path to 4.0 points was significantly easier than the first player. In a tie the computer would place the first player ahead of the second.
If this calculation still does not resolve a tie the next one is used. TBrk (P) measures the performance of the opposition a player faces. This calculation attempts to recognize the performance of the competition that a player met on the day. The math is a bit complicated but in simple terms a win against a strong player who won all his other games is worth more than a win against a weak player who lost every game he played.