釋門歸敬儀 2.11

2.11

七曰奇拜者，謂先屈一膝，即今時所謂雅拜也。一說奇拜但一拜，以答臣下之拜也。

The seventh is called the single-knee bow (qibai), which means first bending one knee; this is what is now called the elegant bow. Another explanation says the single bow is just a single bow used to respond to the bow of a minister.