XML development basics-XML verification code sharing

XML with correct syntax is called "well-formed" XML. The XML verified by a DTD is a "legal" XML. A well-formed XML document with a & quot; well-formed & quot; has the correct syntax. A well-formed & quot; XML document follows the XML syntax rules described in the previous chapters: XML with the correct syntax is called "well-formed" XML.

The XML verified by a DTD is a "legal" XML.

Well-formed XML documents

A "well-formed" XML document has the correct syntax.

A "well-formed" XML document follows the XML syntax rules described in the previous chapters:

XML documents must have root elements

The XML document must have a close tag.

XML tags are case sensitive.

XML elements must be correctly nested

The XML attribute must be enclosed in quotation marks.

 
 
  
   George
  
  
   John
  
  
   Reminder
  Don't forget the meeting this weekend!
 

Verify the XML document

A valid XML document is a "well-formed" XML document, which also complies with the syntax rules of Document Type Definition (DTD:

 
 
  
   George
  
  
   John
  
  
   Reminder
  Don't forget the meeting this weekend!
 

In the preceding example, the DOCTYPE declaration references the external DTD file. The following section shows the content of this file.

XML DTD

A dtd defines the structure of an XML document. It uses a series of legal elements to define the document structure:

 
 
 
 ]>

XML Schema

W3C supports an XML-based DTD replacement named XMLSchema:

The above is the details shared by the XML verification code. For more information, see other related articles in the first PHP community!