The details are described in the Appendix C of the XHTML 1.0 standard. So our ever-popular image example would look like this. The basic idea is to use self-closing syntax for tags where HTML doesn’t want a close tag, like img, br or link, with an extra space before the slash. This is a set of guidelines for making valid XHTML documents that can still more or less be processed as HTML. To enable at least partial use of XHTML, the W3C came up with something called “HTML-compatible XHTML”. When XML and XHTML were first standardized, no browser supported them natively. This gives you better odds of generating valid XML, but it also makes it very easy for a trivial error to completely break your document.
In contrast to the leniency of HTML parsers, XML parsers are required to fail catastrophically if they encounter even the simplest syntax error in an XML document. Second, XML has draconian error-handling rules.
XML DISPLAY IN HTML FOR MAC CODE
In XML (including XHTML), any tag can be made self-closing by putting a slash before the code angle bracket, for example. And others, like div always need to have a close tag. Others, like p may close implicitly based on other content. In HTML, some tags, such as img are always assumed to be empty and close themselves. While very similar in many respects, it has a few key differences.įirst, XML always needs close tags, and has a special syntax for tags that don’t need a close tag. XHTML (eXtensible HyperText Markup Language) is a reformulation of HTML in XML syntax. It is a meta-markup language, like SGML, but one that simplifies many aspects to make it easier to make a generic parser. XML (eXtensible Markup Language) grew out of a desire to be able to use more than just the fixed vocabulary of HTML on the web. This is why it is a good idea to validate your documents. But there are lots of differences in edge cases, because this error handling behavior is not documented or part of any standard. This error-handling is relatively consistent between browsers. Many technically illegal constructs, like misnested tags or bad attribute names, are allowed or safely ignored. HTML as actually used on the web is best described as a custom language influenced by SGML.Īnother important thing to note about HTML is that all HTML user agents (this is a catchall term for programs that read HTML, including web browsers, search engine web crawlers, and so forth) have extremely lenient error handling. SGML is quite complicated, and in practice most browsers do not actually follow all of its oddities. HTML was originally an application of SGML (Standard Generalized Markup Language), a sort of meta-language for making markup languages. The original language of the World Wide Web is HTML (HyperText Markup Language), often referred to by its current version, HTML 4.01 or just HTML4 for short. In particular, it is likely to affect Dashboard Widget developers in a huge way in upcoming WebKit versions. Well, the HTML/XHTML distinction may seem like an obscure topic, but it can have significant practical effects. You may be wondering what the subtitle has to do with the title. This article will attempt to clear up some of that confusion. Or we’re asked why an XML construct like doesn’t actually close the bold tag. We often see questions on the webkit-dev mailing list where people wonder why their seemingly XHTML documents result in HTML output. The relationships among HTML, XML and XHTML are an area of considerable confusion on the web.