最近几年来，地理信息系统无论是在理论上还是应用上都处在一个飞速发展的阶段。 GIS被应用于多个领域的建模和决策支持，如城市管理、区划、环境整治等等，地理信息成为信息时代重要的组成部分之一； “数字地球”概念的提出，更进一步推动了作为其技术支撑的GIS的发展。 与此同时，一些学者致力于相关的理论研究，如空间感知、空间数据误差、空间关系的形式化等等。 这恰好说明了地理信息系统作为应用技术和学科的两个方面，并且这两个方面构成了相互促进的发展过程。
XPath is a language used to select components for XML documents.
XPath is designed for use by XSLT, XQuery, and XPointer. To learn more about XPath, please read our XPath tutorial. To learn more about XQuery, please read our XQuery tutorial. To learn more about XSLT, please read our XSLT tutorial. XPath 1.0 became a W3C recommendation on November 16, 1999. XPath 2.0 became a W3C recommendation on January 23, 2007. XPath 2.0 is a language derived from XPath 1.0 and XQuery. The generation of XPath 2.0 and XQuery 1.0 is homologous, they share a lot of the same syntax, and a lot of the text is consistent. Standard Draft / proposal Recommended time XPath 1.0 Nov 1999 XPath 2.0 Requirements Jun 2005 XPath 2.0 Language Dec 2010 XPath 2.0 Functions Dec 2010 XPath 2.0 Data Model Dec 2010 XPath 2.0 Semantics Dec 2010 XPointer Aug 2002 4.10.1. Tutorials ¶
4.10.2. XPath version ¶
XPath 1.0 ¶
XPath 2.0 ¶
4.10.3. W3C XSL specification and timeline ¶