They are an aspect of bar pairs.
Bar pairs then can form swings; HH, HH, LH <- head & shoulders on a 3 bar form, swing high on the LTF;
3 - LTF swings builds to form a swing on the Intermediate TF,
3 - ITF swings builds to form a swing on the HTF,
at a minimum.
Congestion can include more bars.
It all starts with a single bar for OHLC/OLHC encapsulates a swing within a bar.
