For some link tutorials in the XML guide in the classic forum, there are some additions to supplement, they are also initiator, limited horizons, please ask friends to advice! The English site in http://www.w3schools.com/dtd/default.aspdtd DTD is intended to define the legal build module of the XML document, which determines the internal structure of the XML document through a series of legitimate elements. DTD can declare within your own XML document, or as an external reference
1. Internal Statement If the DTD is included in the XML source file, it will be defined in "DOCTYPE" in "DOCTYPE" in the following syntax format:
Example 1: ]> 2. External Statement If the DTD is outside the XML source file, it will define in "DOCTYPE" in "DOCTYPE" in the following syntax format: Filename> Example 2: This XML document is identical to Example 1, but uses external DTD Document Note.dtd contains defined DTD < ! Element body (#pcdata)> After reading the above introduction, you may have such questions, why do you want to use DTD? 1. Each XML file can be saved by DTD, and your DTD formatted data description is saved. 2. With DTD, independent of the user, and use the common DTD to achieve the purpose of data exchange. Your app can verify whether the data from the outside world is legal through standard DTD, of course, you can also verify your data through DTD.
