What is Pulmonic-contour click?

Pulmonic-contour clicks, also called sequential linguo-pulmonic consonants, are consonants that transition from a click to an ordinary pulmonic sound, or more precisely, have an audible delay between the front and rear release of the click. All click types have linguo-pulmonic variants, which occur as both stops and affricates, and are attested in four phonations: tenuis, voiced, aspirated, and murmured. At least a voiceless linguo-pulmonic affricate is attested from all Khoisan languages of southern Africa , as well as from the Bantu language Yeyi from the same area, but they are unattested elsewhere.