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。
XML Schema 参考手册 完整 XML Schema 参考手册 The complexContent element defines extensions or restrictions on complex types that contain mixed content or only elements. 父元素： ComplexType (? The symbol declaration element can appear zero or once within the complexContent element. ) Attribute Description Id Optional. Specifies the unique ID of the element. Mixed Optional. Specifies whether character data is allowed to appear between children of the complexType element. The default is false. Any attributes Optional. Specifies any other attributes with the non-schema namespace. In the following example, there is a complex type “fullpersoninfo” that is derived from another complex type “personinfo” by extending the inherited type with three supplementary elements: In the above example, the “employee” element must contain the following elements in order: “firstname”, “lastname”, “address”, “city”, and “country”. XML Schema 参考手册 完整 XML Schema 参考手册 Definition and usage ¶
Element information ¶
Grammar ¶
Example 1 ¶
<xs:element name="employee" type="fullpersoninfo"/> <xs:complexType name="personinfo"> <xs:sequence> <xs:element name="firstname" type="xs:string"/> <xs:element name="lastname" type="xs:string"/> xs:sequence> xs:complexType> <xs:complexType name="fullpersoninfo"> <xs:complexContent> <xs:extension base="personinfo"> <xs:sequence> <xs:element name="address" type="xs:string"/> <xs:element name="city" type="xs:string"/> <xs:element name="country" type="xs:string"/> xs:sequence> xs:extension> xs:complexContent> xs:complexType>