Evaluates an XPath 1.0 expression against the XML: location paths with every axis (child, descendant, parent, ancestor, sibling, following/preceding, attribute), name/*/text()/node() tests, predicates with position and last(), unions, comparisons and arithmetic, and the core functions (count, name, string, contains, starts-with, substring, normalize-space, translate, number, sum, round, boolean, not, …). Node-set results list each match with its path and serialized XML; other expressions return a string, number or boolean. Namespaces are matched by their literal prefix. Everything runs locally.
Examples: count(//book) · //book[last()]/title · //title[contains(., 'XML')] · sum(//price) div count(//price)