A is calculated by price action failing to close or open above a fib level yet its high crossing the level. This essentially means price action was too weak to break this level.
The same goes for support levels where the price open and closes above the fib level yet the price low was below. This means the bears where unable to break the and may potentially rebound.
This script uses the 0.764, 0.618, 0.5, 0.382 and 0.236 levels. More can be added to script if asked.
From personal use I use the script to help guide the entry and exit for potential trades aswell as helping mark price targets and exit levels. However i never use this script alone and actively ensure it is used alongside other technical indicators.
Within the script there is also a plotted chart which can help visually aid the trader.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.