XHTML Day 1th: What kind of doctype to choose

Xhtml

The first thing to do when you start making a site that meets the standard is to declare a DOCTYPE that meets your needs. View the original home code, you can see the first line is: "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" > Open some of the standard sites, such as the famous web design software developer Macromedia, Design Master Zeldman's personal website, will find the same code. The code for other standards-compliant sites, such as K10k.net, is as follows: "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd" > So what does the code mean? Are you sure you want to place it? What is DOCTYPE The above code we call the DOCTYPE declaration. DOCTYPE is a shorthand for document type, which is used to indicate what version of XHTML or HTML you are using. The DTD (for example, the XHTML1-TRANSITIONAL.DTD in the example above) is called the document type definition, which contains the rules of the document, and the browser interprets the identity of your page based on the DTD you define and displays it. To create compliant web pages, DOCTYPE declarations are an essential component; Unless your XHTML determines a correct DOCTYPE, your logo and CSS will not work. XHTML 1.0 offers three types of DTD declarations to choose from: (1) Transition (Transitional): A very loose DTD that allows you to continue using the html4.01 identity (but to conform to the XHTML notation). The complete code is as follows: "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" > (2) Strict (strict): Requires a strict DTD, you can not use any of the presentation layer of identity and attributes, for example. The complete code is as follows: "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd" > (3) Framework (FRAMESET): DTD specifically designed for frames page design, if your page contains frames, you need to use this DTD. The complete code is as follows: "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd" > What kind of doctype do we choose? Ideally, of course, a strict DTD, but for most of us who have just come in contact with Web standards, the Transition DTD (XHTML 1.0 Transitional) is the ideal choice (including this site and the transition DTD). Because the DTD also allows us to use the identity, elements, and attributes of the presentation layer, it is also easier to pass the code checksum of the consortium. Note: The above "performance layer identification, attributes" refers to those who are purely used to control the performance of the tag, such as the table used for typesetting, background color identification. The identity in XHTML is used to represent structs, not to implement representations, and the purpose of our transition is ultimately to achieve data and performance separation For example, a mannequin changes clothes. Models are like data, clothes are representations, models and clothes are separate, so you can change clothes at will. The original HTML4, the data and performance is mixed together, it is very difficult to change the form of a one-time. Oh, a little abstract, this concept requires us to gradually understand in the application process. Add: The DOCTYPE declaration must be placed at the top of every XHTML document, above all code and logo.