A trendline drawn along the support or resistance points of various reversal patterns such as head and shoulders, double and triple tops/bottoms.
A line connecting the lows of the head in a head and shoulders formation, or the highs of an inverse head and shoulders. A move under the neckline of a head and shoulders top is bearish; a move above the neckline of an inverse head and shoulders neckline is bullish.
The level that indicates the lows of the head in the head and shoulders formation or the high points in an inverse head and shoulders formation.