Shuāng xián shàng huáyīn 双弦上滑音 (trad. 雙絃上滑音) “Two String Rising Slide”
Sweep the thumb across two open strings in a gesture away from the performer. Press the lower string to match the pitch after it is struck, creating an audible slide.
Ferguson lists this as equivalent to Chongtuo but the term huayin suggests a slide should be audible.