15.2.51. XML Schema sequence element

Element information ¶

父元素： Group, choice, sequence, complexType, restriction (both simpleContent and complexContent), extension (both simpleContent and complexContent)

Grammar ¶

<sequence
id=ID
maxOccurs=nonNegativeInteger|unbounded
minOccurs=nonNegativeInteger
*any attributes*
>
(annotation?,(element|group|choice|sequence|any)*)
</sequence>

(? Declares that the element can appear zero or once in the sequence element. )

Attribute	Description
Id	Optional. Specifies the unique ID of the element.
MaxOccurs	Optional. Specifies the maximum number of times an any element can appear in the parent element. The value can be an integer greater than or equal to zero. If you do not want to set any limit on the maximum number of times, use the string “unbounded”. The default value is 1.
MinOccurs	Optional. Specifies the minimum number of times an any element can appear in the parent element. The value can be an integer greater than or equal to zero. To specify that the any group is optional, set this property to zero. The default value is 1.
Any attributes	Optional. Specifies any other attributes with the non-schema namespace.

Example 1 ¶

This example is a declaration for the “personinfo” element, which must contain the following five elements in order: “firstname”, “lastname”, “address”, “city”, and and “country”.

<xs:element name="personinfo">
  <xs:complexType>
    <xs:sequence>
      <xs:element name="firstname" type="xs:string"/>
      <xs:element name="lastname" type="xs:string"/>
      <xs:element name="address" type="xs:string"/>
      <xs:element name="city" type="xs:string"/>
      <xs:element name="country" type="xs:string"/>
    </xs:sequence>
  </xs:complexType>
</xs:element>

Example 2 ¶

This example is a declaration for the “pets” element, which can contain zero or more dog and cat elements:

<xs:element name="pets">
  <xs:complexType>
    <xs:sequence minOccurs="0" maxOccurs="unbounded">
      <xs:element name="dog" type="xs:string"/>
      <xs:element name="cat" type="xs:string"/>
    </xs:sequence>
  </xs:complexType>
</xs:element>

In recent years, Geographic Information Systems (GIS) have undergone rapid development in both theoretical and practical dimensions. GIS has been widely applied for modeling and decision-making support across various fields such as urban management, regional planning, and environmental remediation, establishing geographic information as a vital component of the information era. The introduction of the “Digital Earth” concept has further accelerated the advancement of GIS, which serves as its technical foundation. Concurrently, scholars have been dedicated to theoretical research in areas like spatial cognition, spatial data uncertainty, and the formalization of spatial relationships. This reflects the dual nature of GIS as both an applied technology and an academic discipline, with the two aspects forming a mutually reinforcing cycle of progress.