Axis: preceding
ElementNode-set
AAA id = a1
BBB id = b1
BBB id = b2b1
AAA id = a2a1 b1 b2
BBB id = b3a1 b1 b2
BBB id = b4a1 b1 b2 b3
CCC id = c1a1 b1 b2 b3 b4
CCC id = c2a1 b1 b2 b3 b4
BBB id = b5a1 b1 b2 b3 b4 c1 c2
CCC id = c3a1 b1 b2 b3 b4 c1 c2