The Superiority of XML

By Willie Voerding

Many companies that produce lots of documentation are striving for single-source documentation.  Single-source documentation is a database of information that can be published in various media and interpreted by different computers (Rude 2002).  This is achieved by tagging or marking the documents so that the data can be retrieved easily from the database.  Tagging documents separates the content and structure of the document from its appearance and can be done using SGML, HTML, or XML.

SGML, or Standard Generalized Markup Language, is the international standard that codes documents with identifying tags so the documents can be distributed in any medium.  It uses generalized tags that identify structural parts of the document so that the document can be distributed through any system.

HTML, or Hypertext Markup Language, is the most frequently used application of SGML used on the web (Flynn 2005).  This language includes code to give instructions on the display of text and graphics on the web by using predetermined tags similar to ones used in SGML.  However, these tags donít describe the exact look of the document because the userís hardware, browser, and preferences that they set can influence the appearance of the document (Rude 2002).  Therefore, different browsers create a different output from the same input.

XML, or Extensible Markup Language, was developed by an XML Working Group formed under the auspices of the World Wide Web Consortium in 1996 with the following goals in mind (Bray 2004):

  • It shall be straightforwardly usable over the Internet.

  • It shall support a wide variety of applications.

  • It shall be compatible with SGML.

  • It shall be easy to write programs which process XML documents.

  • XML documents should be human-legible and reasonably clear.

  • The XML design should be formal, concise, and prepared quickly.

  • XML documents shall be easy to create.

One major difference between XML and HTML involves the tags that mark the structure of the document.  XML allows the user to define their own tags and not rely solely on the predetermined ones, which enhances the database functions of the XML documents.  Because XML marks the structure of the content and not appearance, it can be used to create searchable databases from documents and be a part of any companies single-source documentation system.



Rude, C. 2002. Technical Editing. New York: Longman.

Walsh, N. 1998. A Technical Introduction to XML.

Flynn, P. 2005. The XML FAQ.

Extensible Markup Language 1.0 W3C Recommendation Editors: Tim Bray, Jean Paoli, C.M. Sperberg-McQueen, Eve Maler, Francois Yergean 2004