XPath の preceding axis ってどっち向きの走査だったっけ……
s/preceding/preceding-sibling/
XML Path Language (XPath)
https://www.w3.org/TR/1999/REC-xpath-19991116/#predicates
> Thus, the ancestor, ancestor-or-self, preceding, and preceding-sibling axes are reverse axes; all other axes are forward axes.
reverse axis 、そんな概念あったな……