About positioning Xpath
Q: // difference and / of
expression to describe the
nodename select all child nodes of this node.
/ Select from the root node.
// Select the document matches the selected node from the current node, regardless of their location.
. Select the current node.
.. select the parent node of the current node.
@ Select Properties.
Constantly updated ...
https://www.w3school.com.cn/xpath/xpath_syntax.asp