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。
XHTML is a HTML written in XML format. XHTML refers to Extensible Hypertext markup language XHTML and HTML 4.01 are almost the same. XHTML is a stricter and purer version of HTML XHTML is a HTML defined as a XML application. XHTML is a W3C recommendation released in January 2001. XHTML is supported by all major browsers Many pages on the Internet contain “bad” HTML. If you view it in a browser, the following HTML code works perfectly (even if it does not follow the HTML rules): XML is a well-formed markup language that must be tagged correctly. There are some different browser technologies in today’s technology world. Some of them run on computers, while others may run on mobile phones or other small devices. Small devices often lack the resources and ability to explain “bad” markup languages. So-by combining the strengths of XML and HTML, XHTML was developed. XHTML is a redesigned HTML as XML. XHTML DOCTYPE is mandatory. In HTML, some elements can not be nested within each other, like this: In XHTML, all elements must be reasonably nested within each other, like this: Example of error: Correct example: Example of error: Correct example: Example of error: Correct example: Example of error: Correct example: Example of error: Correct example: Example of error: Correct example: Add a XHTML Add Change all elements to lowercase Turn off all empty elements Modify all attribute names to lowercase Add quotation marks to all attribute values 11.29.1. What is XHTML? ¶
11.29.2. Why use XHTML? ¶
<html><head><metacharset="utf-8"><title>This is an non-standard HTMLtitle><body><h1>non-standard HTML<p>This is a paragraphbody>
11.29.3. The most important difference compared to HTML: ¶
Document structure ¶
XML in namespace attribute is mandatory 、 、 11.29.5. XHTML elements must be reasonably nested ¶
<b><i>Bold and Italic Textb>i>
<b><i>Bold and Italic Texti>b>
11.29.6. The XHTML element must be related to a closed tag ¶
<p>This is a paragraph<p>This is another paragraph
<p>This is a paragraphp><p>This is another paragraphp>
11.29.7. An empty element must contain a close tag ¶
branch:<br>horizontal line:<hr>picture:<imgsrc="happy.gif"alt="Happy face">
branch:<br/>horizontal line:<hr/>picture:<imgsrc="happy.gif"alt="Happy face"/>
11.29.8. XHTML element must be lowercase ¶
<BODY><P>This is a paragraphP>BODY>
<body><p>This is a paragraphp>body>
11.29.9. Attribute name must be lowercase ¶
<tableWIDTH="100%">
<tablewidth="100%">
11.29.10. Attribute values must have quotation marks ¶
<tablewidth=100%>
<tablewidth="100%">
11.29.11. Attribute abbreviations are not allowed ¶
<inputchecked><inputreadonly><inputdisabled><optionselected>
<inputchecked="checked"><inputreadonly="readonly"><inputdisabled="disabled"><optionselected="selected">
11.29.12. How to convert HTML to XHTML ¶
go to your web page xmlns property is added to the html element.