Quantified expressions
The expression some $x in E1 satisfies E2 returns true if there is an item
in the sequence E1 for which the effective boolean value of
E2 is true. Note that E2 must use the range variable
$x to refer to the item being tested; it does not become the context
item. For example, some $x in @* satisfies $x eq "" is true if the context
item is an element that has at least one zero-length attribute value.
Similarly, the expression every $x in E1 satisfies E2 returns true if every
item in the sequence given by E1 satisfies the condition.
From XPath 4.0, quantified expressions can include a type declaration, previously available only in XQuery. (Implemented from Saxon 13.)