How to cite this paper

O'Connor, Charles, Antony Gnanapiragasam and Michael Hepp. “ProofExpress: An Online, Browser-Based XML Article Proofing System for STM Journals.” Presented at International Symposium on Native XML User Interfaces, Montréal, Canada, August 5, 2013. In Proceedings of the International Symposium on Native XML User Interfaces. Balisage Series on Markup Technologies, vol. 11 (2013).

International Symposium on Native XML User Interfaces
August 5, 2013

Balisage Paper: ProofExpress

An Online, Browser-Based XML Article Proofing System for STM Journals

Charles O'Connor

Workflow Automation Specialist

Dartmouth Journal Services

Charles has a degree in biology and had previous lives as an indexer, copyeditor, and video store clerk before getting involved in this XML thing.

Antony Gnanapiragasam

Workflow Automation Specialist

Dartmouth Journal Services

Antony has masters degrees in computer science and public administration and works as a system architect.

Michael Hepp

Director, Technology Strategy

Dartmouth Journal Services

Mike has a bachelor's degree in printing management and sciences and is the project leader for ProofExpress.

Copyright © Dartmouth Journal Services 2013


For a browser-based XML article proofing system to function well in a journal publishing workflow, it must embody two virtues: It must have a very shallow learning curve, because the majority of users will be encountering it for the first time, and they may have no knowledge whatsoever of XML. It must also have a comprehensive and accurate change-tracking feature that allows editors to accept and reject changes without breaking the XML. A system designed for a publication services company with many publisher-customers must have the additional virtue of being highly customizable to account for wide variations in journal styles and the particular needs of online hosts.

To achieve usability, we based ProofExpress on LiveContent Create (formerly Xopus), a browser-based, WYSIWYG XML editor, and designed form-based tools to guide users in the creation of more complex XML structures. Our change-tracking feature employs denormalization of nested elements to granularly expose all edits and a rule engine that protects the structure of the XML by governing the order of acceptance and rejection of edits. XML configuration files control the content of the nodes added by the tools, allowing ProofExpress to accommodate the differences in, for example, reference, citation, and footnote styles used by journals that publish articles in XML that conforms to the JATS 1.0 DTD.

Table of Contents

User Interface
Change Tracking
The Limitations of XML Differencing
Rule Engine for Changes Acceptance and Rejection
Custom Elements and XML Denormalization


The advent of PDFs represented a leap forward for article proofing. No longer did proofs need to be printed out and either mailed or faxed to the author for correction. The PDF could be delivered instantly over the Internet, and the author could view and annotate the PDF on a computer in a different environment, using a different operating system. (Of course, that does not stop them from printing the pages out, correcting them by hand, and mailing or faxing them back.) The question then becomes, how can we bank the gains that were made in delivery and interoperability and take them to the next level? The answer, of course, is online XML editing.

The clearest advantage of an online, XML-based proofing system is that everyone involved can work on the same document from copyediting through final corrections. This stands in contrast to PDF-based proofing, where authors and editors may mark up different PDFs, which are then given to a typesetter to transfer the corrections. Sources of error at this stage include the misinterpretation of sometimes ambiguous corrections and the rekeying itself ( A new PDF is then generated, and another review cycle is initiated. PDF proofing is thus both inefficient and prone to error due to the degree of manual intervention. As attractive as an XML-based proofing system can seem from a workflow standpoint, however, it will come to nothing unless it is adopted. An online, XML-based article proofing system designed for science, technical, and medical (STM) journals must be easy to use for authors, editors, and publishers and maintain the XML in good shape for the typesetting system and the online providers that host the resulting content.

Authors of STM journal articles can be many things--researchers, engineers, students, doctors. One thing they often are not is readers of instructions. (Many jobs in publishing, from copyeditors to developers of editorial software, depend on this fact.) In addition, authors may not be especially eager to learn new software. When Dartmouth Journal Services (DJS) instituted PDF annotation as our preferred method of proof review, many authors pointed out that they had written their paper in MS Word and did not appreciate having to learn how to use the annotation tools in Acrobat Reader. (We use eXtyles to apply structure to authors' Word files. After copyediting, we again use eXtyles to export JATS XML.) So, the ideal system will give authors a set of tools similar to those they are accustomed to in word processing programs.

Editors must review the corrections made by authors, and to do so, they need an accurate change-tracking mechanism. In addition, they need a way to accept or reject the changes that an author has made to their proof. A likely solution, and the one we tried first, is XML differencing. However, XML differencing must work around the longest common subsequence problem ( Whatever the solution arrived at, for example, applying a semantic cleanup or a cleanup based on string length (, XML differencing can only tell you how two versions of a piece of text are different, it cannot tell you what was done to make the versions different. Thus, editors would be faced with accepting or rejecting these differences, not the actual edits made by the author.

A problem particular to publication services companies is accommodating the wide variations in journal style across their publisher-customers. The DTDs based upon the NISO Journal Article Tag Suite 1.0 (JATS 1.0) ( are to varying degrees descriptive, not prescriptive. They are silent, for example, on questions of what symbols to use in footnotes, whether to use numbered or author-date reference citations, and whether items in ordered lists should have labels or not. Another complication arises from the needs of the different online hosts that a publication services company must deliver XML to. One online host may require that a <glossary> appear within the <back> element, whereas another may want it within the <notes> in the <front>.

User Interface

The great majority of proof corrections made by authors and editors are simple text edits: insertions, deletions, and formatting changes. As ProofExpress is intended to be a web-delivered application, SDL LiveContent Create (formerly Xopus; was a natural choice to base the system upon. LiveContent Create is a continuously validating XML editing environment that allows authors to make text corrections using tools familiar to users of word processing programs. They can insert and delete text without having to enter a particular text editing mode. They can cut, copy, paste, and format text using toolbar buttons or keyboard shortcuts. They can insert new paragraphs and sections. All of these edits can be made without any knowledge of the underlying XML structure.

To allow authors to add or edit more complex XML structures such as citations, references, and links, we not surprisingly settled on a form-based approach. In its simplest implementation, fields in the forms correspond directly correspond to elements that will be added to the XML. Rather than using element names for the field labels, ProofExpress uses natural language labels that authors are likely to interpret correctly. When the author completes and submits the form, the system adds the correctly structured XML to the file.

Figure 1: Insert Journal Reference Form

The form for adding references uses natural language labels such as Journal Title and Page Range rather than element names such as <source> and <fpage>/<lpage>, respectively.

In addition to providing a way for authors to add more complex XML structures to an article, forms can also restrict author input to choices that make sense in the context of the particular article. That is, when the author wants to add a cross-reference to some other part of the document, the system can examine the relevant nodes and offer a list of choices in a dropdown. The form can then give feedback to the author to confirm the correct choice. For example, the Add/Edit Reference Citation tool reads the list of available citations and puts identifying information into the dropdown. When the author chooses a reference and submits the form, the system adds the cross-reference. Standard variable items that the author should not be expected to keep track of, for example, in this case, the correct rid attribute, are added by the system.

Figure 2: Add/Edit Reference Citation Form

The add/edit reference citation form offers the author a list of references to choose from. When the author chooses from the list, the full reference is shown below in a read-only box as a confirmation that the correct reference has been chosen. This confirmation is especially important because multiple references can share the same authors and years.

Change Tracking

The one absolutely essential feature of any proofing system is change tracking. Editors must have the ability to see exactly what corrections authors have made, not only to ensure that these corrections conform to journal style, but also to confirm that the authors have made no changes to data or to claims that would require the article to undergo another round of peer review. A great advantage can be gained if the change-tracking feature also includes an easy way to accept and reject changes. Although such features are available in desktop XML editors such as Arbortext (, no online XML editor has a change tracking feature that is adequate for the task. LiveContent Create itself has a change tracking feature, but it's features are rather limited. It tracks insertions and deletions, but not formatting changes. In fact, as we discovered when we tried to build upon the native feature, deletions of text that include formatted text are not tracked at all.

The Limitations of XML Differencing

When we first started building ProofExpress, we naturally gravitated towards differencing to serve as the basis for our change-tracking feature. This method promised to be accurate while placing no burden on the user's perception of the performance of the application. However, we soon ran into difficulties related to how differencing engines work around the longest common subsequence problem. If we take the raw output of a differencing engine, we may get an accurate representation of the difference between the original and edited versions of the text, but it may not tell us what the author actually did. For example, if an author changes the sentence "I say cheese to you" to read "I say oh pleeze to you", the engine will depict the change as "coh pleesze" (where underline=insertion and subscript=deletion). This is not only difficult to read, but it gives the editor multiple changes to accept or reject, instead of one deletion and one insertion, inviting the possibility of introducing error during review.

Attempting to overcome this problem by applying a cleanup parameter or otherwise grouping changes can lead to a loss in the granularity of changes. Changes within changes will not be marked individually as changes, which is a problem if they should be dealt with discretely. For example, if you take "<p>hello world</p>", italicize it and add text in the middle to form "<p><italic>hello silly italic world</italic></p>", the XML differencing engine DeltaXML ( will accurately identify the former as the original text and the latter as the revised text. What it will not tell you specifically is that two changes have occurred: text has been italicized and text has been added. An editor rejecting the italic formatting of the text could inadvertently reject the insertion as well.

Figure 3: Results from the DeltaXML "Sandbox"

The original node, <p>hello world</p>, was revised to <p><italic>hello silly italic world</italic></p>. The diff presented by DeltaXML is correct, but it does not serve journal production workflows because it does not mark the internal insertion as a discrete change.

Rule Engine for Changes Acceptance and Rejection

Editors must not only be able to see the changes made by authors, but they must have an easy way to accept or reject these changes. So, we built a widget that lists all of the changes and allows the editor to accept or reject them. (This feature is also available to corresponding authors that share editing with colleagues.) All decisions about acceptance or rejection are considered provisional until the article moves to the next stage in the workflow, making it easy for the editor to reverse a decision if necessary.

A potential problem arises when accepting and rejecting changes. If the system does not enforce an order of decision making, then the process may break the XML. Consider this case: Author1 adds some text to a paragraph. Author2 deletes the entire node where this paragraph resides. If the editor accepts both the insertion of the text and the deletion of the node, the text would be left outside of its proper parent node, breaking the XML structure. To alleviate this problem, we group nested changes together and force editors to act upon the outer change before they can act on the inner change. According to our rule engine, a particular action by the user on an outer change may or may not force the accept/reject decision on the inner change. In this case, acceptance of the outer deletion forces the rejection of the inner insertion. Rejection of the outer deletion would allow either rejection or acceptance of the inner insertion. These rules can be applied through multiple layers of nesting.

Figure 4: Acceptance and Rejection of Edits

Unless a rule engine is imposed, the process of accepting and rejecting changes could break the XML. In this case, accepting the deletion of the paragraph node forced rejection of an internal insertion (indicated by the entry being grayed out).

Custom Elements and XML Denormalization

To create a change-tracking system that notes not just the difference between the original file and the edited version, but actually records what the author did, we used the extensive set of event handlers in LiveContent Create to add custom elements to the XML on the fly. Doing so turned out to be rather more difficult than it first seemed, as there can be many ways to perform the same edit. For example, there are many ways to delete text. You can delete character-by-character using the Backspace or Delete keys. You can select a text range and use Backspace or Delete. You can select and Cut or select and type over. All of these methods of deletion should be presented in the same way to the user, but they had to be dealt with individually through the event handlers.

The changes that we made to the JATS schema to accommodate our track changes feature reflect the different ways an edit can be performed as well. Again using the example of deletion, the LiveContent Create event handlers provide different information depending on whether deletions are done to a block of text at once or are done character-by-character and, in addition, whether the text being deleted contains a formatting node or not. As a consequence, we use one deletion tag for deletions that are done character-by-character and contain formatting nodes and another tag for deletions done to blocks of selected text or text that does not include a formatting node. Another modification of the JATS schema is the addition of "unformatting" nodes. If a user makes text bold, the system naturally adds a <bold> tag. If another user removes the formatting from that text, an <unbold> tag is applied.

When the track changes elements are added to the XML, a set of attributes are added as well. These give the system information about who made the change at what time, whether the change has been accepted or rejected by the editor, etc. In the example of different users toggling on and off formatting, the element reflects the current state of the formatting while attributes contain the history of how the current state was arrived at. These attribute values also inform the XSLTs that are run when a user toggles on the Track Changes Show mode. These XSLTs perform a variety of functions, for example, merging contiguous insertions or deletions made by the same author that may have been performed using different methods.

Figure 5: Toggling Formatting On and Off

In this example, user "cl1" made the text bold, user "cl2" removed the bold, user "cl3 reapplied the bold, and user "ca", finally, removed the bold. The element <unbold> reflects the final state. The attribute @fmhist records the users who applied bold, while @unfmhist records the users who removed bold.

Changes made by an author should not always be merged; sometimes they need to be broken up. For our accept/reject rule engine to work properly, the Track Changes tool must show how changed nodes are nested within each other. Also, insertions and deletions should always be the outside changes when they occur in relation to changes in formatting, because the acceptance or rejection of an outside formatting change should have no effect on an internal insertion or deletion. To achieve the desired result, the XSLTs that are run on toggling to Track Changes Show mode denormalize nodes related to Track Changes and move insertions/deletions to the outside of formatting nodes.

Figure 6: Denormalization of Formatting Nodes

Formatting nodes are denormalized and placed on the inside of insertion or deletion nodes to serve the functioning of the accept/reject rule engine.

Figure 7: Denormalized Nodes in the Track Changes Tool

Acceptance or rejection of a formatting change should have no effect on the status of insertions and deletions. Therefore, formatting changes should appear "inside" insertions and deletions.


A publication services company, DJS delivers XML for over a hundred journals from different publishers. These journals differ in the style they use for everything from the casing of headings to the italicization of foreign words. Many of these differences must be accounted for in ProofExpress. For example, some journals use numbered citations while others use author-date citations. Among those that use author-date citations, some list one author before "et al." while others list six, some place a comma before the year while others do not, some put citations in brackets while others put them in parentheses, etc. The tool used for adding and editing citations must know not only the correct elements and attributes to add, it must know what the text content of the citation will be. Adding an additional level of complication, DJS delivers XML to several online hosts, and each of these has its own requirements that must be accommodated as well.

To customize ProofExpress, each article is transmitted by our production management system with a set of configuration files. In addition to XSLTs and CSS file that control display of the article, a set of XML files (naturally!) controls the output of the program's editing tools. A good example of a tool that requires configuration is the Add/Edit Footnote/Affiliation/Correspondence tool. Journals can use numbers, letters, or symbols to cite footnotes. The numbers used for citations may start with affiliations, continue through the correspondence line, and be used for author footnotes as well, or different citation schemes could be used for each. The same type of footnote may appear in the <author-notes> wrapper in one journal but in an <fn-group> in the <back> in another. The following is a snippet from a footnote configuration file that describes a financial disclosure footnote:

This snippet tells the system what kind of footnote this is, what fn-type attribute to apply, where it is placed and where it can be cited, what formatting, if any, should be applied to the <xref> (tag abuse!), and the prefix used in its id attribute. However, description of the footnote is not sufficient; the order that footnotes are assigned indicators and placed in each respective group must be spelled out:

When different citation indicators can be used together, such as in the author line, the system needs to know the order to place them:

Finally, when symbols such as asterisks and daggers are used, their order of use must also be specified:

The use of XML files for configuration of ProofExpress provides distinct advantages. The files are easily generated and allow very granular control of elements of style. Use of configuration files obviates the building and maintenance of a complex administrative interface. New elements can be added as new configuration points are uncovered. As a bonus, we are looking into developing XSLTs that will pull information from these configuration files and construct Schematron rules to ensure that articles coming into the system conform to the same style points specified by the configuration.


Designing and building a browser-based XML article proofing system has been a challenge. ProofExpress must let users with no prior knowledge of XML easily make any possible edit. It must track every change, and give editors a tool to review the changes and accept or reject each one individually without breaking the XML. The same tools used across all journals must be configured to output different XML to accommodate the styles of each.

The rewards of having such a system are great as well, and we may eventually expand its usage to copyediting (though not to authoring; we have no control over authors until their articles are accepted and in our production workflows). By allowing all work to be done on a single file, ProofExpress increases efficiency as it removes potential sources of error. Schematron validation can be applied during the correction cycle instead of after back-end conversion, when the errors it uncovered would be more expensive to fix. In addition, having such a system opens up new possibilities in the journal production workflow. Notably, ProofExpress enables us to add fully automated page generation to our workflows, even when the system that creates the PDF cannot "round-trip" the XML. A new PDF of the article can be generated at any stage, simply by feeding the revised XML to the page-generation system. This capability puts the entire production process where it should be, in the hands of authors and editors.