What are key levels used for?

They are your named price references — previous-day high, overnight low, VWAP — and they are what lets the app tell you which levels you actually trade well.

A key level is a name, not a number. You are not storing "23,410"; you are storing that you trade pdHigh, so that every trade tagged against it can be pooled and judged.

That is what turns a chart habit into a statistic: not "I like previous-day levels" but what your results at them actually are.

The list is a master list. Change it here and every dropdown across the app updates immediately.