In the early days of the World Wide Web, when people handcrafted websites in raw HTML code, hypertext was a revelation.
Many thought that the ability to link to other content would result in a new paradigm for journal articles and a richer environment for researchers. But it did not happen.
Today, web and document links are used without a moment's pause, but they usually take the user "somewhere else", to another document, perhaps, or to the top of a web page.
So-called "enriched content" offers researchers the opportunity to incorporate another layer of information into their papers in addition to standard content.
However, examples of such usage - such as an internal link from a graph to the source data file, or from a chemical formula to a 3D graphic of what it creates - remain rare.
The usual arrangement for research papers and reports is the portable document format (PDF), originally developed by Adobe for document exchange and an open standard since 2008.
Most publishers and researchers use PDFs with the primary aim of making documents portable and in particular to ensure consistency in printing across different systems.
Enriched content, if there is any, is limited to a few external links.
But this situation is changing as publishers strive to improve their products and exploit new technology.
IJsbrand Jan Aalbersberg, vice-president of content innovation at Elsevier, believes enriched content will form an important part of the evolution of the scholarly article.
But he warned that if researchers are to adopt it, it must fit in with their natural research workflow, with minimal extra effort required.
"Ultimately, the goal is for each journal to have its own set of discipline-specific enriched content," he told Times Higher Education, citing examples including protein viewers in molecular biology and Google Maps in the earth sciences.
Some of this enriched content has already been implemented in Elsevier's journals, but it tends to be available exclusively online because it requires links to online tools, databases, websites and libraries.
Another innovator is the University of Manchester, which has developed Utopia Documents, a cross-platform desktop application that links standard PDF files with "enriched models produced by publishers or the community".
By adding content links, or annotations, as a separate "layer", the software leaves the original PDF files unchanged.
Originally developed for Portland Press, which publishes the Biochemical Journal, it is now being used by the Royal Society of Chemistry (see box left).
Steve Pettifer, senior lecturer in computer science at Manchester, said that the developers were also talking to other publishers.
He said the additional editorial workload of adding links for enriched content typically amounted to only about 10 minutes per article.
As well as using built-in tools, readers can "explore" keywords or names using discipline-specific searches.
They can also share comments on a document via a server, provided both parties have access to the original PDF file; this avoids the potential for breach of copyright if copies of an annotated article are sent to others.
But Cameron Neylon, a biophysicist at the Rutherford Appleton Laboratory who speaks regularly on issues of open science, does not believe enriched content will add as much to the scientific enterprise as its advocates suggest.
Simple window dressing?
He told THE that enhancing journal articles with enriched content risked implying that "the article is the research" and the "be-all and end-all", when researchers should, in his view, be rewarded for producing non-narrative output, such as images or data sets.
Adding enriched content to the traditional format is just "window dressing", he argued.
"Nobody is asking if this is terribly well suited to communicating research findings. If I want to choose a new microscope, I don't want to read 100 papers. I just want to compare images from a range of microscopes," he said.
Dr Neylon said that researchers should publish more, but in a different way. He noted that most of the research record - particularly laboratory notes, figures and negative results - is never published.
But publishing such material is now easy, he said, through sharing sites such as FigShare, SlideShare, YouTube, tagged pictures in Flickr, or narrative sites such as Storyful.
His preferred approach to the evolution of the journal paper is "to take papers apart and pull them back together, but in a modular way", using different media and software to present the research record in a "compelling narrative".
This should make more use of social media, Dr Neylon argued.
"This does not mean the traditional narrative paper is going away," he said, "but archiving and curation should not be conflated with communication. We don't have to print to communicate."
Chemical romance: a discipline made for enriched content
The Royal Society of Chemistry, via RSC Publishing, is pioneering the use of enriched content in its journals.
According to Colin Batchelor, its senior informatics analyst in Cambridge, enriched content has "clear applications in the chemical and biomedical spheres".
However, he said that it was less obvious how it could be applied to physics and mathematics.
Chemistry is the subject "par excellence" for such content, he said, because it makes extensive use of chemical dictionaries and formal, unambiguous chemical-naming conventions.
This means software can be used to parse the text, using algorithms to interpret chemical names and generate links that can even apply to new chemical compounds.
Compound names in the text can then be linked directly to the society's ChemSpider database, where readers can discover additional data.
Initially, authors were asked to add enriched content themselves but most failed to do so, so papers had to be "hand-curated", which Dr Batchelor said required extra effort.
But a more automated approach has now been developed. This required a "one-off" investment in the technology but was much more scaleable, he said.
The society is also extending the process to its 170-year-old archive.
Richard Kidd, informatics manager at the society, said that the project was "a milestone for how chemical science information can link together across the web".
One of its key aims is to make it easier for readers to find other relevant material for their research - not just to enhance content, he added.