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Semantic, Structured Authoring

By Tony Self


Sir Tim Berners-Lee is passionate about something he calls the "Semantic Web". Well respected as the inventor of the World Wide Web, Berners-Lee recognises the deficiencies of HTML, and sees the solution lying in the power of XML. Extensible Markup Language is a standard developed and maintained by the World Wide Web Consortium (W3C), an international committee that guides the World Wide Web "to its full potential by developing protocols and guidelines".

Despite being produced by the W3C, it would be wrong to think of XML as a Web enterprise. XML is bigger than the Web. XML is a format for storing all types of data, and that includes "information", "content", instructions, procedures, stories, and ideas. It is a format for storing knowledge. It will be the format for DVD settings, phone directories, cricket statistics, traffic light sequences, spacecraft design, Help systems and procedure manuals. For technical writers, this is not some insignificant development. Nor is it something technical for only programmers to worry about. It requires a change in the way we write, and in the processes we use to write.

This article looks at the impact of the introduction of semantic markup and structured authoring on the world of technical writers, editors, Help authors and content developers. This article is not specifically about the Semantic Web movement itself, but about the implementation of semantic concepts in the documentation field.

This article was first published in January 2005, and revised and updated in March 2007.

The "Semantic Web"

So what does Berners-Lee mean by the term "Semantic Web"? To quote the man himself, the Semantic Web is "an extension of the current Web in which information is given well-defined meaning, better enabling computers and people to work in co-operation". That helps a little. An overly academic explanation explains "the attempt to augment syntactic information already present in the Web with semantic metadata in order to achieve a Semantic Web that human and software agents can understand."

Perhaps a better explanation is that the "Semantic Web" is an attempt to make the information on the Web behave more like a text database, where information is better categorised, structured, organised and labelled. Rather than describe a blob of information as simply a paragraph (through an HTML <p> tag), it may describe the same blob by its nature, such as water quality (through an XML <water_quality> tag). The content is contained within tags that describe the information within.

A Semantic Web would therefore be much easier to work with; for machines and humans to process, re-organise, re-use, re-format and comprehend.


Metadata is data about data. Information that describes or classifies information. Even if we've never used the term "metadata" before, we've actually know it well. An index is metadata. It helps describes the information, but it is not part of the core information itself. The details of a novel's publisher is part of a novel's metadata. It's not part of the story, but it is important information.

The name of the person who approved a company policy is part of that policy's metadata. The release date of a Help system is metadata. Now wouldn't it be great if we could locate information based on a comprehensive, well thought out collection of metadata? It'd be like using a super-indexing system. Wouldn't it be great if we could "Google" for a sea kayak reseller in Melbourne with Sunday opening hours, and find one or two results, not 688? (Don't believe me? Check what Google really returns .)

Metadata is important to the concept of the "Semantic Web". It is just as important to non-Web information.

Where Does XML Fit In?

XML is the technology underpinning the "Semantic Web". It provides the rules framework for storing, retrieving and displaying information, not just for the Web, but for use within software applications, and for creating printed documents.

XML is not really a language in itself, but a set of rules for creating languages. There is an XML language called CML, designed for storing and displaying information about chemicals. There is an XML language called MathML, designed for storing and displaying mathematical formulae. There is an XML language called WML, designed for storing information for display on mobile phones. There is an XML language called DocBook, designed for storing procedure manuals and other forms of documentation. AML is another XML language, designed for storing and displaying user assistance information for the Help system for Windows Vista.

We would recognise some of these XML applications as pure "data" storage formats. But others we would identify as "document" or information storage formats. One more example might help explain this distinction. An XML language called "Office Open XML" is a format now used by Microsoft Word and Excel to store word processing documents and spreadsheets. The old RTF-based .doc format is a thing of the past.

XML offers a technical solution to a very human communication problem. In the Information Age, we are overwhelmed by quantity of information, but underwhelmed by the quality!

The Challenge for Technical Writers

The world is awash with information, and we have all experienced the symptoms of " information overload ". Attention spans are reducing. Readers are becoming more impatient, and are wanting to quickly scan information rather than read it thoroughly. As creators of information, of content, technical writers need to confront this problem.

The tried and trusted narrative style of writing, where we open an empty page and start writing, is no longer appropriate. The standards we previously worked within are no longer sufficient. We need to have more formal hierarchies and structures for our information; it needs to be more granular, and it needs to be framed in metadata.

Semantic, Structured Authoring

The Macquarie Dictionary defines semantic as "pertaining to meaning". Semantic Authoring aims to give more meaning to the information being written. If we are going to not only write down the words we want to communicate, but at the same time describe what it is we are writing, then we have to adopt a structured approach to writing.

For example, if we are writing a procedure which states that the address section of a form must be completed, it is just as important to describe this part of the procedure as a step (or a rule, or a policy, or a legal requirement), and to describe the circumstances when this instruction applies.

In short, once we start to provide a semantic overlay to our writing, we find we need to use structures to work within. In the example above, being able to "tag" the instruction as <policy> or <step> would give the instruction its semantic "key". So that our writing is consistent, and so that the semantics of our work can be used for indexing, or searching, or some retrieval, we would need to decide on a standard range of "tags". If we wanted to collaborate with other writers, then we would need to negotiate and agree on that standard set of tags.

In fact, that process has already happened. IBM pioneered a standard called DITA, which defines a "tag" structure suitable for authoring, producing and delivering technical information. DITA stands for Darwin Information Typing Architecture, and was developed by technical writers. (By the way, the "Darwin" is a homage to the evolutionary theorist Charles Darwin, because DITA uses the principles of specialisation and inheritance.) DITA is now an open standard, and is guided by a committee of technical writers. The types of tags in DITA include <topic>, <title>, <shortdesc>, <prolog>, <body> and <concept>.

DITA is, of course, an XML language. The rules for XML languages are formalised in a "Document Type Definition" (DTD) or "schema". DITA isn't the only XML schema on offer for technical writers. DocBook is another.

DocBook is another open standard, designed for technical documentation. It has tags such as <article>, <section>, <title>, <articleinfo> and <pubdate>.

Writing to an XML schema is similar to filling in a form, and this is the primary distinction between "structured authoring" and the traditional "narrative authoring". You don't start with a blank page; you start with an empty form. You don't work within the hard-to-enforce rules of a style guide; you work within the strict rules of a schema. In narrative (sometimes called "style-based" or "template-based") authoring, the structure of the document is implied by its typography. In structured authoring, the structure of the document is explicitly defined by its tags.

Separation of Content from Presentation

One of the original principles of the World Wide Web was the separation of content from presentation. The idea was that the author would provide a simple structure for the document by using a simple set of tags (<h1>, <h2>, <p>, etc), and the viewing program (or browser) would determine how that information was presented to the reader. The author didn't define how an <h1> heading would be presented - the browser software did. Most browsers were designed so that the reader could override the default settings, giving the reader the power to choose how a document looked.

Unfortunately, this principle was lost in a period known as the "browser wars", where new browser-specific tags were added without the consent of the W3C. Once the <font> tag was introduced, the separation of content from presentation ideal was diluted. Trying to shut the gate after the horse had bolted, the W3C eventually introduced the concept of Cascading Style Sheets (CSS), which re-invigorated the idea of separating content from presentation. If you have never looked at the CSS Zen Garden, then do so now. It is a CSS showcase, where just one page of content is presented in hundreds of different ways just by linking to different style sheets.

XML not only re-introduces the concept of separation of content from presentation, but takes it to a new level. The tags used in HTML were really presentational tags. By nominating a paragraph as <h1>, the author was really defining an aspect of the presentation to the reader. An <h1> was a heading. A heading is a presentation or formatting term more than a content term. An XML schema allows more specific tags, such as <concept> and <conbody>, to be used. No inference about presentation can be drawn from those tags. So presentation can be truly separated from content. XML tags and their attributes contain the document's metadata.

Writers write the content. Someone else decides on the presentation.

Separation of Content from Delivery

The most powerful technical benefit of XML is the ability to also separate content from delivery. When we write a structured XML document, we don't need to concern ourselves with how the information will be delivered to the reader. Will it be delivered as a paper document? As a PDF? On a Palm Pilot or other PDA? As a CHM file? As a Web page? In a specialised browser? Within Microsoft Excel? It doesn't matter.

Writers write the content. Someone else works out how it will be delivered to the reader.

This concept is fairly new to the technical writing world, but isn't so new in other writing professions. Newspaper journalists submit stories (in an XML format normally) to their editors. They write the stories on a computer, and they have no say in formatting or delivery decisions. A news story may end up being syndicated to a specialised Web site in Singapore, it may be printed on the front page of the "Sydney Morning Herald", parts of it may be sent as an SMS message to news subscribers, or it might end up on the Fairfax Web site. The story may be presented in 14 point Times Roman, or it might be in 6 point Tahoma. Journalists write the content. Someone else takes care of presentation and delivery.

Knowledge Markup

Semantic authoring has been defined as "to compose information content semantically structured according to some ontology". (If you've never encountered the word ontology before, the dictionary defines it as "the branch of philosophy concerned with the nature of being".) A much better explanation of semantic authoring is "knowledge markup". Simple tags such as <policy> aren't the only way in which knowledge is categorised, indexed and labelled within XML. Tags can contain attributes (such as the id attribute in <section id="upg11">), and metadata can be stored in tags separate from the content itself (such as <author><firstname>Tony</firstname><surname>Self</surname></author>).

Authoring Tools

If we are going to write our procedures, instructions, policies or Help content into an XML format, we are probably going to need an authoring tool. XML documents are stored in ASCII format, so in theory, we could use Notepad as our editor. Alternatively, we could use a more specialised XML editor, or even an HTML editor (most can cope with XML code).

The determining factor, though, is what schema we are writing to. If we are writing to DocBook, it would be best to use a tool that is "DocBook-aware". If we are writing to the Chemical Markup Language standard, we should write using a "CML-aware" tool. Most XML authoring tools on the market tend to be generic, rather than specific to a particular XML language.

As a language becomes more popular, the demand for a specific tool rises, and the market fills the need. XML being an open standard, and XML documents being stored in ASCII, it is easy to chop and change between tools. The screen capture below shows a quickly-assembled editing tool for an in-house XML standard used for online Help. If you look closely, you might recognise the application as being a Microsoft Access form. Access can save content to XML, using the database field names as XML tag names. In the example, the information in the Title field will be saved within a <title> tag.

          Screenshot of XML Authoring Tool
Screenshot of XML Authoring Tool

The most common semantic markup languages for documentation are DocBook and DITA. PTC Arbortext Editor, JustSystems XMetaL, Syntext Serna, XMLmind XXE, DITA Storm, or perhaps OpenOffice, are good choices for authoring documentation content; some tools support DITA, others DocBook, and others both. And these tools are growing in sophistication and maturity rapidly.

There's no reason why technical writers can't start writing their content in DocBook, or DITA, or a custom XML language for that matter, now. In fact, many already are. (This article was written in DocBook.) But what about the writing skills and techniques? Are they the same as for narrative authoring?

Structured Authoring Techniques

Structured authoring is a concept or methodology, and XML is one of the technologies through which structured authoring is implemented. (AuthorIT and Adobe Structured Framemaker is another alternative to XML.) Writing within an XML structure is like filling in a form. There are some parts of the form that we have to fill out, other parts that we need to expand upon, and other parts that are not relevant. The XML schema specifies what elements are compulsory, which ones can be repeated, which ones are optional, and the hierarchy of those elements. Once we commit to writing to a schema, we cede control of these elements. If our content doesn't seem to fit the schema rules, we have to make it fit!

Writing structured content takes some time to get used to. Research by Adobe Systems indicates that that structured authoring is initially more expensive, but quickly becomes very efficient. The graph below shows the relative cost of structured (they call it Single-Source Authoring) versus Unstructured Authoring over the life of a document.

Source: Adobe FrameMaker Tips and
Source: Adobe FrameMaker Tips and Techniques

The most important structured authoring technique is letting go of the old idea of control of layout, structure and format. Structured authoring can be liberating, rather than restrictive. Technical writers no longer have to worry about widow-lines, kerning, heading styles, bolding, page layout and auto-numbering!

Structured Authoring requires an understanding of the elements of the schema being used, the purpose of each element, and the rules for their use. For example, DITA specifies a number of topic types, such as Task, Concept and Reference. Within DITA, a Task topic is intended for a procedure describing how to accomplish a task; lists a series of steps that users follow to produce a specified outcome; identifies who does what, when, where and how . A Reference topic is for topics that describe command syntax, programming instructions, other reference material; usually detailed, factual material .

The design of a document is also quite different. Many technical writers use a brainstorming technique to create a document skeleton, and then create a proposed table of contents or document structure, before starting to write the content. This technique does not work as well for structured authoring; particularly for DITA, where documents are a collection of numerous "topics", rather than a small number of larger chapters. "Atomising" or "granularising" the information into smaller chunks becomes another important structured authoring technique.

The application of metadata is also a new challenge for many writers. Although indexing may be a familiar task, applying metadata as topics are being created requires more discipline.

Presentation and Delivery

If XML separates content from presentation from delivery, so that writers can concentrate on writing, who will be responsible for presentation? And for delivery? And how is the content integrated with the presentation and delivery mechanism?

A new role, perhaps with a title of "information architect", is likely to take up the presentation and delivery responsibilities. The role is quite a technical one, but still requires an understanding of language, readability and communication. XML content is transformed to suit a delivery mechanism through another XML technology called XSLT. The acronym stands for XML Stylesheet Language - Transformations, and is a cross between a database query language and a macro-programming language. XSLT can instantly transform DocBook XML into HTML, or into another XML language (such as WML or AML), or into an organisation chart graphic (using SVG), or even into RTF! Information can be sorted, or selected based on metadata criteria. A related technology called XSL-FO can be used to transform XML content into print outputs such as PDF and PostScript.

For Web delivery, CSS still has a role. In most browsers, XML documents are CSS-aware. It is possible to display an XML document in an appealing format without transforming to HTML by simply applying an appropriate CSS stylesheet.

JavaScript and server-side scripting languages are also XML-aware, so XML content can be transformed by a Web server or as a Web Service. (But let's not get into Web Services now! That's a whole new XML field!)

Re-Using Content and Single-Sourcing

One of the benefits of granularised content (smaller chunks), when coupled with the power of XML transformations, is that a blob of content can be written once and re-used many times.

XML is by nature a true single-source environment. With content completely separated from presentation and delivery, it becomes easy to generate different outputs simply by applying a different transformation. By connecting the XML content to one XSLT file you might generate WML. Connecting to another might produce an HTML Help file.

Not Constraining: Liberating

It is important to understand that XML rules are not intended to be constraining. The X in XML stands for extensible. The rules can accommodate all sorts of information, and ways of expressing that information. So XML languages, or standards, can be created to accommodate all sorts of information. And so they have been.

Structured authoring results in increased productivity, greater consistency and improved standardisation. In a world where technical writers have greater demands put upon them, structured authoring offers an opportunity to deliver higher quality for less effort.


Creating documentation within a structured authoring process is an exciting challenge for technical writers. Structured authoring is a necessary consequence of the move to XML schemas for storage and delivery of technical and procedural documentation. The benefits of providing a semantic framework for documents are many, and writers can concentrate on writing rather than presentation and delivery.

Using XML, technical writers can improve the quality of information, and reduce the quantity of unnecessary information. Semantically-based structured authoring techniques can result in better documentation, provided we learn how to use those techniques wisely and properly.

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Some XML Acronyms

eXtensible Markup Language
XML Stylesheet Language - Transformations

Darwin Information Typing Architecture
XML Schema Definition
Document Type Definition
Microsoft Assistance Markup Language or Micro-Array Markup Language
XML Stylesheet Language - Formatting Objects
Scalable Vector Graphics
Wireless Markup Language