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。
RDF instance ¶
This is a few lines of a CD list:
Title | Artists | The country | Company | Price | Year |
|---|---|---|---|---|---|
Empire Burlesque | Bob Dylan | USA | Columbia | 10.90 | 1985 |
Hide your heart | Bonnie Tyler | UK | CBS Records | 9.90 | 1988 |
These are several lines of an RDF document:
Bob Dylan USA Columbia 10.90 1985 Bonnie Tyler UK CBS Records 9.90 1988 . . . The first line of this RDF document is the XML declaration. This XML declaration is followed by the root element of the RDF document: xmlns:rdf Namespace, which specifies that elements with the prefix rdf come from the namespace “ http://www.w3.org/1999/02/22-rdf-syntax -ns#”.” xmlns:cd Namespace, which specifies that elements with the prefix cd come from the namespace “ http://www.recshop.fake /cd#”.” Elements: W3C 的 RDF 验证服务 It is very helpful when you learn RDF. Here you can experiment with RDF files. The RDF online validator parses your RDF document, checks its syntax, and generates tables and graphical views for your RDF document. Copy and paste the following example into the W3C RDF validator: After you parse the above example, the result will look something like this.RDF online verifier ¶