XML

Word Map

MIME, XHTML Modularization (Links open onsite in a new window)

XML stands for eXtensible Markup Language. It was developed as a common tool to structure information to be shared on the Web and between software systems. XML is a way of tagging text for meaning, instead of appearance.

In other words, XML can be used to organize the content of text by tagging with meaningful information. Although the "tags" are conceptually the same as the "fields" in a database in terms of organization, the major difference between XML files and database files is that the former are regular text files which can be viewed and edited using any standard text editor.

The file can be searched and queried like a regular database using tools like Xpath or Xquery, and edited using Xforms. (A web-based tutorial on these tools can be found at http://www.w3schools.com/xml.)

Elements that were deprecated in xhtml 1.0 are just invalid or not supported in xhtml 1.1. Most of these were elements presentational, and the W3C is moving towards separation of information and its presentation.

The name attribute on anchors, for instance, is now replaced by the id attribute. and instead of three different doctypes, there is only one: not transitional, strict or frameset but just xhtml 1.1.

The purpose of the change is making xhtml documents that will be portable across many kinds of devices.

1. All of the elements deprecated in XHTML 1.0 Strict have been removed completely from XHTML 1.1

2. You can't serve XHTML 1.1 as HTML the way you can XHTML 1.0 transitional.

MIME Type

It is the MIME type that determines what type of document you are using. Any document, including a document authored with the intention of being XHTML, served as text/html is technically an HTML document.

Such "HTML-compatible" content is sent using the HTML media type (text/html) rather than the official Internet media type for XHTML (application/xhtml+xml). When measuring the adoption of XHTML to that of regular HTML, therefore, it is important to distinguish whether it is media type usage or actual document contents that is being compared.

XHTML 1.0 Strict is the XML equivalent to strict HTML 4.01, and includes elements and attributes that have not been marked deprecated in the HTML 4.01 specification.

XHTML 1.0 Transitional is the XML equivalent of HTML 4.01 Transitional, and includes the presentational elements (such as center, font and strike) excluded from the strict version.

Modularization provides an abstract collection of components through which XHTML can be subsetted and extended. The feature is intended to help XHTML extend its reach onto emerging platforms, such as mobile devices and Web-enabled televisions. The initial draft of Modularization of XHTML became available in April 1999, and reached Recommendation status in April 2001.

A Brief History

The first XHTML Family Markup Languages to be developed with this technique were XHTML 1.1 and XHTML Basic 1.0. Another example is XHTML-Print (W3C Recommendation, September 2006), a language designed for printing from mobile devices to low-cost printers.

In October 2008 Modularization of XHTML was superseded by XHTML Modularization 1.1, which adds an XML Schema implementation.

XHTML Modularization 1.1

XHTML 1.1 evolved out of the work surrounding the initial Modularization of XHTML specification. The W3C released a first draft in September 1999; Recommendation status was reached in May 2001. The modules combined within XHTML 1.1 effectively recreate XHTML 1.0 Strict, with the addition of ruby annotation elements (ruby, rbc, rtc, rb, rt and rp) to better support East-Asian languages. Other changes include removal of the lang attribute (in favor of xml:lang), and removal of the name attribute from the a and map elements.

Although XHTML 1.1 is largely compatible with XHTML 1.0 and HTML 4, in August 2002 the HTML WG (renamed to XHTML2 WG since) issued a Working Group Note advising that it should not be transmitted with the HTML media type. With limited browser support for the alternate application/xhtml+xml media type, XHTML 1.1 proved unable to gain widespread use. In January 2009 a second edition of the document was issued, relaxing this restriction and allowing XHTML 1.1 to be served as text/html.

XHTML 1.1 Second Edition (W3C Proposed Edited Recommendation) was issued on 7 May 2009 and rescinded on 19 May 2009.

XML Benefits

  1. XML files are simple text files. Software that can read a text file can read an XML file. Nothing is happening at "byte" level in an XML document. It follows then, like text files, that XML is platform independent. XML created on a UNIX system has a very high probability of working on a Windows PC. These two points explain one of the real and important benefits of XML; long-term, cross-platform data storage. Data stored in XML is accessible to anything or anyone that can read text.
  2. Anytime two or more systems need to communicate, a common language is required. The platform compatibility and ease of use of XML have made it a favorite as the common language for many systems to speak.
  3. Anytime two or more systems need to communicate, a common language is required. The platform compatibility and ease of use of XML have made it a favorite as the common language for many systems to speak.

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