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。
The property is Attribute can add additional information to the element Attributes are generally described in the opening tag Attributes always appear in the form of name / value pairs, such as: name= “value”. Attribute values should always be enclosed in quotation marks. Double quotes are the most commonly used, but there is no problem with usingsingle quotes. Tip: in some individual cases, for example, the attribute value itself contains double quotes, then you must use single quotes, such as name=’John “ShotGun” Nelson’ Properties and property values are not case-sensitive. However, the World wide Web Consortium recommends lowercase attribute / attribute values in its HTML 4 recommendation. The new version of (X) HTML requires lowercase attributes. Check out the complete list of HTML attributes: the HTML tag reference manual. The following lists the attributes that apply to most HTML elements: Attribute Description Class Define one or more class names for the html element (class namesare introduced from the style file) Id Define the unique id of the element Style Specifies the inline style of the element (inline style) Title Describes additional information about the element (used as a toolbar) HTML element to provide additional information. 11.6.1. HTML attribute ¶
HTML element can set properties 11.6.2. Attribute instance ¶
HTML Links are made up of label definition. The address of the link is href property to specify: Example ¶
<ahref="http://www.runoob.com">This is a linka>
11.6.3. Common reference property values for HTML properties ¶
11.6.4. HTML hint: use lowercase attributes ¶
11.6.5. HTML attribute reference manual ¶