Comparison of the Ca IIλ8662 difference line profile (black) with the blue wing of O Iλ8446 (red) and the right wing of Ca IIλ8542 (green) in velocity space. The profiles of O Iλ8446 (red) and Ca IIλ8542 are normalized to their left and right peak, respectively, and shifted downwards for clarity. All profiles exhibit identical line features, namely a pronounced left peak ➀, the same lopsidedness and characteristic small-scale features in the central profile ➁, and a triple-peaked (trident) red peak ➂.