XML-属性类型

1。CDATA：一般文字。EX：

<?xml version="1.0"?> 

<!DOCTYPE employees_information [

<!ELEMENT employee_data (name)>

<!ATTLIST tel name CDATA #IMPLIED>

]>

2。Enumerated：某一个属性由一组列表中选取一个。EX：

<!ELEMENT employee_data (name)>

<!ATTLIST  name  isp(pro1|pro2|pro3.....)>

3。NMTOKEN：此类型的属性值只能是英文、数字、-

4。ENTITY：在声明属性值时可以使用实体引用。EX：

<!ELEMENT employee_data (name)>

<!ELEMENT name  English #PCDATA>

<!ENTITY orc "val1">

<name English="&orc">

5。ID：属性值只能出现一次。EX：

<?xml version="1.0"?>
<!DOCTYPE employees_information [
  <!ELEMENT employees_information (employee_data+)>
  <!ELEMENT employee_data (name, age, sex, address, email, tel)>
  <!ELEMENT name (#PCDATA)>
  <!ATTLIST name emp_id ID #IMPLIED>
]>

<employees_information>
  <employee_data>
    <name emp_id="E101">Chin Lee</name>
    </employee_data>
 
  <employee_data>
    <name emp_id="E102">C.Y. Shen</name>
  </employee_data>
</employees_information>

6。IDREF：它是对ID的引用。当某个属性值引用另外一个ID类型的属性值时可以申明为IDREF.EX:

<?xml version="1.0"?>
<!DOCTYPE employees_information [
  <!ELEMENT employees_information (employee_data+)>
  <!ELEMENT employee_data (name, depu)>
  <!ELEMENT name (#PCDATA)>
  <!ELEMENT depu (#PCDATA)>
  <!ATTLIST name emp_id ID #IMPLIED>
  <!ATTLIST depu emp1_id IDREF #IMPLIED>
]>

<employees_information>
  <employee_data>
    <name emp_id="E101">Chin Lee</name>
    <depu emp1_id="E102"/>
  </employee_data>
 
  <employee_data>
    <name emp_id="E102">C.Y. Shen</name>
    <depu emp1_id="E101"/>
  </employee_data>

7。#IMPLIED：XML属性可有可无

8。#REQIRED：它表示必须要出现（对属性的内容没有限制）。EX：

<?xml version="1.0"?>
<!DOCTYPE employees_information [
  <!ELEMENT employees_information (employee_data+)>
  <!ELEMENT employee_data (name,email)>
  <!ELEMENT name (#PCDATA)><!ELEMENT email (#PCDATA)>

  <!ATTLIST name nick_name NMTOKENS #REQUIRED>
  <!ATTLIST email ISP (eranet | htnet | hinet) #REQUIRED>
]>

<employees_information>
  <employee_data>
    <name nick_name="White Man">Chin Lee</name>

    <email ISP="htnet">clee@mail.ht.net</email>
    <tel>(020)2186206</tel>
  </employee_data>

</employees_information>

9。FIXED：属性值必须固定且必须出现。EX：

<?xml version="1.0"?>
<!DOCTYPE employees_information [
  <!ELEMENT employees_information (employee_data+)>
  <!ELEMENT employee_data (email)>
  <!ELEMENT email (#PCDATA)>
  <!ATTLIST email ISP CDATA #FIXED "mdservice">
]>

<employees_information>
  <employee_data>
   <email>clee@mail.ht.net</email>
  </employee_data>
</employees_information>