Abstract: Geography Markup Language（GML） is XML technology applied to GIS fields and has become the de facto standard of data representation, transmission and exchange over Internet. GML document query algorithm has already become the current research focus. The structure of GML documents and the characteristic of spatial data are studied, and a new indexing structure GB-Tree is designed, which is a kind of index on spatial nodes in GML documents. The idea of XML Twig pattern queries is introduced to GML documents queries and a new kind of GML query algorithm（GMLTwigStackGB） is proposed. GMLTwigStackGB algorithm keeps the characteristic and advance of Twig pattern algorithm and has all functions of spatial queries. Experiments show that GMLTwigStackGB algorithm performs better efficiency in some kinds of queries over GML documents.

Key words: Geography Markup Language（GML）, Twig pattern, spatial data, Geographic Information System（GIS）

摘要： GML文档是XML技术在GIS方面的应用，成为空间数据在Internet上的实际表示、传输和交换的标准。目前，GML文档的查询是GIS领域的研究热点。对这一问题，研究了GML文档的数据特点和结构特点，设计了一种新的索引结构——GB树，GB树是专门针对GML文档中空间数据节点的索引结构。将XML Twig模式查询思想引入GML文档查询，借助GB树的索引特点，提出了GML文档的Twig模式查询算法——GMLTwigStackGB。GMLTwigStackGB算法保留了XML文档Twig模式查询算法的优势和特点，具有完整的空间查询功能。测试实验表明，该算法能够高效地满足GML文档上的各种数据查询。

关键词: 地理标识语言（GML）, Twig模式, 空间数据, 地理信息系统（GIS）