The shallowest trendline from the prior day

There is a shallowest possible bull and a shallowest possible bear trendline every day. These trendlines have some predictive power as to where the price can turn and trend. For example, the shallowest bear TL from the prior day from HOD and b21 caused a reaction that led to a large move. If the final bar is the highest or lowest bar of the day, then you can use a TCL instead, which has lower predictive use.

Note that when the price gaps far from the prior day's action, the shallowest TL from the prior day may never be tested and you should not wait for it.