XPath 2.0 is an expression language that allows the processing of values conforming to the data model defined in [XQuery/XPath Data Model (XDM)]. The data model provides a tree representation of XML documents as well as atomic values such as integers, strings, and booleans, and sequences that may contain both references to nodes in an XML document and atomic values. The result of an XPath expression may be a selection of nodes from the input documents, or an atomic value, or more generally, any sequence allowed by the data model.
The name of the language derives from its most distinctive feature, the path expression, which provides a means of hierarchic addressing of the nodes in an XML tree.
XPath is designed to be embedded in a host language such as [XSLT 2.0] or [XQuery]. XPath has a natural subset that can be used for matching (testing whether or not a node matches a pattern); this use of XPath is described in [XSLT 2.0].
XQuery Version 1.0 is an extension of XPath Version 2.0.
XPath also depends on and is closely related to the following specifications:
* [XQuery/XPath Data Model (XDM)] defines the data model that underlies all XPath expressions.
* [XQuery 1.0 and XPath 2.0 Formal Semantics] defines the static semantics of XPath and also contains a formal but non-normative description of the dynamic semantics that may be useful for implementors and others who require a formal definition.
* The type system of XPath is based on [XML Schema].
* The built-in function library and the operators supported by XPath are defined in [XQuery 1.0 and XPath 2.0 Functions and Operators].
下午把 Functions & Operators 列表抄了一份，觉得 date time 相关的 fn/op 定义真是太别扭了。集合操作，还有 uri/QName 操作是没有用过的。
那么 XPath20 本身只是讲定位吗？