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。
CSS (Cascading Style Sheets) describes how the document is displayed. To learn more about CSS, please read our CSS tutorial. As a W3C recommendation, CSS1 was released on December 17, 1996. On January 11, 1999, this recommendation was revised. As a W3C recommendation, CSS2 was released on January 11, 1999. CSS2 adds support for media (printers and hearing devices) and downloadable fonts. CSS3 plans to divide CSS into smaller modules. Starting with CSS3, modules will be defined separately, for example, css4 selectors can be defined in CSS3 modules. The W3C defines the following CSS attributes: Print Properti Mobile device Properti TV attribute Standard Draft / proposal Recommended date CSS 1 Dec 1996 CSS 1 (Revised) Apr 2008 CSS 2 May 1998 CSS 2.1 Jun 2011 DOM Level 2 Style Specification Nov 2000 CSS Style Attributes Oct 2010 CSS 3 Namespaces Module Sep 2011 CSS 3 Selectors Sep 2011 CSS 3 User Interface Module Jan 2012 CSS 3 Fonts Module Feb 2013 CSS 3 Color Module Jun 2011 CSS 3 Backgrounds and Borders Module Jul 2012 CSS 3 Text Module Nov 2012 CSS 3 Lists and Counters Module May 2011 CSS 3 Line Module May 2002 CSS 3 Basic Box model Aug 2007 CSS 3 Multi-column Layout Module Apr 2011 CSS 3 Ruby Module Jun 2011 CSS 3 Speech Module Mar 2012 CSS 3 Paged Media Module Oct 2006 CSS 3 Generated content for Paged Media Module Nov 2011 CSS 3 Values and Units Module Aug 2012 CSS 3 Cascading and Inheritance Jan 2013 CSS 3 Template Layout Module Nov 2011 CSS 3 Media Queries Jun 2012 CSS Mobile Profile 2.0 Dec 2008 CSS TV Profile 1.0 May 2003 CSS Print Profile 1.0 Oct 2006 4.7.1. CSS tutorial ¶
CSS1 ¶
CSS2 ¶
CSS3 ¶
CSS4 ¶
4.7.2. CSS attribute ¶
4.7.3. W3C CSS specification and timeline ¶