A series of three sequentially higher horizontal lines used to identify possible areas of support and resistance for the price of an asset. The position of the center line is plotted by calculating the difference between the highest high and the lowest low for the asset price over a period of time and dividing it by 2. The top and bottom line are drawn 1/3 and 2/3 of the difference, respectively, between the same high and low that are used to calculate the center line. The use of Tirone levels is similar to that of Fibonacci retracement, and both are interpreted in the same way. They both determine the position of the lines by using a percentage of the difference between a high and a low. Both Tirone levels and Fibonacci retracement use 50% as one of the possible support/resistance levels.