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Visual-Meta Introduction

Last updated on August 1, 2019


Visual-Meta is an approach to make document’s meta machine and human readable by adding an appendix to the end of the document, based on BibTeX, with all the information needed to cite the document (author, title, date etc.) as well as clearly stating the values of any data (such as tables, lists advanced layouts etc.) and glossary terms.

This visually (as plain text in the document) metadata can then be parsed by a Visual-Meta aware PDF reader to enable functionality such as copying text and pasting it as citation in one step.

Putting the metadata visually into the document means that even if the document format is changed or the document is printed and scanned, the data will still be a part of the document and compatibility with legacy readers is maintained since they will only see the metadata as plain text.

Adding human readable appendices to a PDF document which usefully describe the semantics of the document and also making it machine readable offers many benefits and workflow improvements in the academic document space, while adding no document overhead beyond a few plain text pages at the end of the document. This approach keeps compatibility with legacy PDF software Readers while opening up rich opportunities for augmented Readers; Legacy Readers will simply show a normal PDF with an appendix with BibTeX style information.



Visible-Meta Augmented Readers can provide the user with as rich interactions as can be provided in a custom authoring environment–the publishing and freezing onto PDF is no longer a limitation. Advanced interactions can include:

  • Copy As Citation using a simple copy command, with all citation information added to the clipboard payload for use by Visible-Meta aware applications on Paste.
  • Instant Outline based on the document specifying heading formatting.
  • Dynamic Views, such as the one implemented in Liquid | Author could be stored as data not only images.
  • Server Access. Repositories can extract information for large scale analysis.
  • Glossary Support. Glossary terms could be added to the appendix.
  • High Resolution, Document Based Addressing. The Name of the document is not the same as the Title and this can be be used to address by document and not location and support High-Resolution Addressing.
  • & more, to be discovered.



For an author this approach means that they can embed more rich information in their document with a minimum of effort and be sure of the robustness of the information.

It allows the reader a much faster way to cite with a higher degree of accuracy and more access to the original data and interactions.

Augmented textual communication. Using the appendices to describe the document content, such as the formatting of headings and citations as well as the use of glossaries, can allow the reading software to present the document to the readers preference without loosing the creator’s semantics.

Server Friendly which allows for large scale citation and other document element analysis. University of Southampton’s Christopher Gutteridge, one the of the people behind the university repository, elaborates on this.

Institutions can worry less about the cosmetics of citations and benefit from more documents cited being checked and read.

This could put an end to the absurd academic time-waste of nit-picking how citations should be displayed: Let the teacher/examiner/reader specify how the citations should be displayed, based on the document having described in the appendix how they are used and therefore the reader can re-format the the readers tastes.

Universities still get to dictate the default handing-in formatting but the same document could be displayed in any format the reader chooses.



Visual-Meta export is built in to the Liquid | Author word processor and parsing it can be done by the Liquid | Reader PDF reader application, both produced by the author of this article, Frode Hegland:

Video demonstration of the concept (less than two minutes long):



Examples and description of the format is posted: Visible-Meta Example & Structure.


Document Name

Note that the ‘document_name’ is distinct from the title and can be set automatically by the authoring software to help identify the document through search later:



Adoption Support

The first implementations will include links to actual code for how to add this into other developer’s projects, dramatically reducing the implementation overhead.


Legacy Support

When using a supported Reader, the user can download a PDF and copy the BibTeX export format on the download page, then open the PDF in Reader and click to ‘Assign BibTeX’ and it will be applied as an appendix and saved (along with a tag stating which source was used and when), same as if it was natively exported with Visual-Meta. Only the citation information will be provided in this way–formatting etc. will not be available



Legacy Augmentation



When using a supported Reader, the user can download a PDF and copy the BibTeX export format on the download page, then open the PDF in Reader and click to ‘Assign BibTeX’ and it will be applied as an appendix and saved, same as if it was natively exported with Visual-Meta. Only the citation information will be provided in this way–formatting etc. will not be available.


Reader applications can also send non-visible-meta PDFs to a server, such as Scholarcy to have the Visible-Meta extracted and appended.




This work grew out of work on Liquid | Author: Visible-Meta Origins.


How This Relates To My PhD

This work has grown out of my PhD work at the University of Southampton under Dame Wendy Hall and Les Carr. It aims to solve infrastructure issues which hamper citation interaction and visualisations: Visual-Meta & my PhD.


Known Issues

There are many issues to be worked out, including how to refer to different authors of different chapters and what exactly to encode.

Published inAugmented Text ToolsAuthorFuture Of TextLiquid | ViewLiquid | View PitchNotes On...PhDRich PDFThoughtsVisual-Meta


  1. vint cerf

    This reminds me a little of the NROFF, WordPerfect formatting that was explicitly embedded in the text except that this proposal puts it into an appendix. This also sounds a little like CSS in HTML – but made explicitly visible. In terms of digital preservation this explicit mechanism has value in the sense that if you can read the text, you can also read the metadata. It is still necessary to be able to understand the semantics of the metadata of course.

    • Thanks yes, I agree. An additional benefit is that it should make it easier for developers to add support for this.

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