Hyperlink Power & Permanence — an exploration of improving the information experience via permanent links and links to specific pages and parts of online PDF files, by Tim Gill

Moonpear Consulting LLC
“Improving the customer information experience”
document management — information design & access — product feature requirements — technical writing — usability

Hyperlink Power & Permanence
©2007 Timothy David GILL

Overview

In years of working in a variety of software development environments, I have always become involved in efforts to deal with the organization’s document management problems, since those problems would always get in the way of getting my "real job" done. As hypertext technology, the Web and Adobe’s PDF format became more widespread in the 1990’s and document management software started to make inroads later that decade, I was delighted to see the possibilities emerging to finally allow decent solutions.

Two features of software in this domain that I have used with good effect, but whose larger possibilities have intrigued me more, are the permanent URL feature of some document management systems (like Xerox’s DocuShare) and intra-document targets in hypertext systems, which can be used in both HTML and PDF documents:

A permanent URL referencing a document is one that never changes, even if the document gets moved around in some logical ordering scheme. This means that other documents can embed links to the document without having to worry that the link will break in a few months time when someone reorganizes the logical collection of documents.

An intra-document target is a location or page, anywhere within a document, to which a hypertext hyperlink can point. When an author creates a link from her document to an intra-document target in another document, the result is similar to opening a book to a certain page in front of someone else and saying "That information is on this page." This permits one to be precise in referencing existing information.

These two capabilities each make it much easier to confidently refer to existing information. This in turn means that it is easier to avoid the need or tendency to write duplicate information—it increases the re-use of existing information and makes possible efforts to continuously improve the ultimate reference information on a topic, since it will get referenced more and more. This can reduce overall effort and increase the value of particular documents, making a process of constant improvement more worthwhile. Within a single enterprise, this power can be harnessed more effectively.

But the real power comes from using both these capabilities together. Few authors would want to put links to targets within another document, even if it can save them from writing their own version of the information that lies there, if they have no confidence that the target document will be there to view when the link is traversed by a reader at some point in the future. And I believe that this power is particularly evident when the target document containing the intra-document links is a large PDF file. More and more large documents are in the PDF format, and being able to refer to a relevant page, or sub-section, or drawing buried deep in such a document, can be very useful.

l think that these two capabilities are significantly underused and that a serious effort within an enterprise context—with the appropriate tool vendor support as necessary—could yield powerful benefits. I am most interested for this article in the intra-document targets within PDF files, since I believe that the PDF format has achieved a level of acceptance with the public at large that makes it the standard for what most people think of as "electronic documents". (Most of my friends are now comfortable with—and even prefer—getting user guides for their home electronics and appliances as PDF files.)

Basic Examples of These Capabilities

NOTE: The links below that link to a PDF file (they are named numerically as "demolink-<n>") will open that file within your browser and not in a separate Acrobat window only if the browser is configured with the PDF plug-in that provides that functionality. I know that Internet Explorer and Firefox have such plug-ins, and other browsers may. I believe that the desirability and convenience of the combination of permanent URLs and intra-document links is much greater if you have this plug-in; so if clicking on any link to a PDF file below gives you a pop-up window to open the file in Acrobat Reader or to save it, you should consider installing the plug-in. If you have the plug-in and know that it works, then you will see the linked-to PDF document in your browser window.

Permanent URL
I use the term permanent URL here in the context of the capability as provided by a document management system within an enterprise. But this term is clearly related to similar terms and ideas, such as PURL (and the PURL service offered by the OCLC) and permalinks as used in the blogosphere.

The Xerox product DocuShare provides a mechanism for a permanent URL—it assigns a unique number to a document when it is first entered into the system. All documents also have a location in a hierarchy, and the document can be found by searching or browsing in the system, but that hierarchical location can and does change as the hierarchy is reorganized to meet evolving organizational needs. But the numeric URL does not change.

For example, the publicly accessible DocuShare site at Oklahoma State's Division of Agricultural Sciences has a document Madagascar Hissing Cockroaches: Information and Care that was put into the system 4 years ago. This demolink-1 to that article uses the DocuShare numeric URL to access it (note the number 2827 at the end of the URL, which is http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2827), and that URL has remained constant for 4 years. (You could also find the document by browsing in DocuShare, which might take you to the folder where it currently resides in the logical hierarchy, or by using DocuShare to search for it (try the word "Madagascar" in the search field)).

Intra-Document Target
The two most common intra-document targets exist in HTML and PDF files:

The W3C HTML standard provides for intra-document targets, called anchors, in HTML documents. These are targets anywhere within the document that can be referenced from other points in the same document or from another. A URL with an anchor causes your browser to go to that position in the target document, not just to the top of the document. Intra-document targets referenced from elsewhere within the same document are powerful for moving around within a large single document (browse the HTML standard linked to earlier in this paragraph to see this power). But this use is not the focus of the article.
PDF files can be opened from a link in an HTML document (and from a link within another PDF file, but we’ll defer that discussion for now). Once opened, there are action commands to direct the Acrobat reader to go to a specific location of the PDF file or to display it in certain ways.

The easiest specific location action is to go to a specific page. The following link goes to page 31 of a Congressional Resolution, which happens to be the beginning of the Title IV section of that document: demolink-2 (this URL is not a DocuShare URL, and may move in the future).

The more specific action available when linking to a PDF file is to go to a specific target within the document, where the target is what Adobe has called a named destination; these are named locations within the file and can be placed there in various ways. The following link goes to a specific section of a support document at the Adobe web site: demolink-3 (this URL is also not a DocuShare URL, and may move in the future).

The syntax of the URL given in these 2 links uses the notation that Acrobat expects for actions: the open parameters following a # character at the end of the usual HREF value giving the address of the PDF file; this is similar to the syntax used in HTML files as well (the fragment identifier).

An Example of Combining The 2 Capabilities

Combining these capabilities (a permanent URL and an intra-document target) allows a permanent hyperlink to a precise page or section of information to be possible. For example, you can send e-mail to someone as brief as "To see what I mean, refer to the 2 diagrams at demolink-4 in that 2005 paper" or include a similar link in any document you are writing. (Notice that the URL used in demolink-4 contains both the DocuShare number for the document and the PDF action commands needed to display the diagram).

And the link will never break…

Summing Up

I believe that the power of combining these two capabilities could be made apparent with a coordinated effort in a relatively large enterprise document management environment.

Imagine the benefits over a period of years of an organizational cultural shift in which increasing numbers of documents are re-used and improved through that re-use…
Imagine FAQ’s that are mostly links to the right section of the best reference document on a topic, and that reference gets improved constantly...
Imagine a corporate culture in which adding to the knowledge base of the company is valued, and the authors of the most linked-to documents are rewarded at performance review time…
Imagine a company whose customers could more easily find the detailed, current information they need on using a popular product, augmented by user feedback…

Issues
There are some issues that I think would need to be addressed in such an effort. These include:

Some PDF readers do not support the open parameters for PDF files that are integral to the thesis of this article. For example, the PDF reader on Apple's iPhone and iTouch do not respect suffixes such as #page=33 or #nameddest=table3. (Imagine the potential uses if they did!).
If your browser failed to open one of the PDF files at the proper page, you may have encountered one of them—it appears that browser or Acrobat caching interferes with the ability of the action commands to work properly on any access to the document after the initial one—as if once you use one open parameter you cannot use another on the same document.
Tools need to be available to support the generation of the named destinations within PDF files from authoring tools and the identification of existing named destinations in already-created PDF files. And the tools need to make it easy for knowledge workers to learn and use the capabilities.

But such things await a serious effort at a large company to make this idea work for them and their customers. (Are you interested? I am—contact me).

Last revised: July 14, 2009

Timothy GILL
Moonpear Consulting
36 Hickory Drive
Maplewood NJ 07040