Companion books are typically glossariesfor example, The Oxford Companion to Shakespeare but there are also companions that deal with aspects of their subject in more depth . To produce companions in the past, it was necessary to have enough material for a complete book. These days, however, there is companion content on the Internet that is only a few pages in length.
Imagine open content: As articles are increasingly published using computer-based devices, it is possible to imagine that users could invoke companion content directly, i.e., by pointing at the relevant item or place in the article, rather than having to access the companion separately.
In order to connect companions to their articles in this way, there must be technical standardspreferably independent industry standardsthat are implemented in the devices used and to which the articles and their companions conform. More important, however, authors must agree to their content being connected in this way . Content that is "open" to such connections is analogous to an open IT system, which allows customers and third-party vendors to connect independent hardware or software components via agreed-upon interfaces .
While there are currently no open-content articles with connected companions from which to draw examples, it is at least possible to conjure up examples based on existing real articles:
Few modern works have attracted as diverse companion content as Patrick O'Brian's Aubrey-Maturin historical novels set in the early 19th Century . His two principal characters (Aubrey: a sea captain, and Maturin: a ship's surgeon) first meet while attending a musical performance in Minorca. Music is a part of their friendship and throughout the novels the two play together during their voyages. A companion CD of music from the period was published in 1996 entitled "Musical Evenings with the Captain" . Were the novels to be published in an open content form, the reader could invoke the relevant piece of music directly from the text. For example, the reader could suspend reading in order to listen to Mozart's oboe quartet in F major at just the point in The Yellow Admiral at which it is played .
Puddings and other dishes of the period are served up on Aubrey's English warships. Lobscouse and Spotted Dog: Which It's a Gastronomic Companion to the Aubrey/Maturin Novels  is a companion book of the food of the period. In an open content form these recipes could be connected to descriptions of the meals in the novels so that the reader could find out immediately what, for example, "lobscouse" is, and how it is cooked.
Hopefully it is obvious that there are many other opportunities for companions to make connections to these novels: biographies of the historical characters, technical data and diagrams of 19th-century ships, glossaries of the medical terms of the period, and so on. In the future, not only might companions be bought as articles in their own right but also for connection to the content on which they are based. There are a number of ways for companion authors and artists to obtain reward for their creations; open content just offers them more opportunities.
The connection between a companion and its open-content article is a technologically layered process. The author or creator of an article of content will not necessarily have foreknowledge of its future companions, and the author or creator of a companion will not necessarily have knowledge of other companions or of those yet to come. It is, therefore, incumbent upon the creator of each companion to make its own connections with the underlying article.
The term "companion" is really a product rather than a technical term. The technical requirement is more basic: A specification associates one piece of content with another so that a connection between them can be implemented in the device they "co-habit". A collection of pieces of content that have been connected may add up to what might be described as a companion in current publishing vernacular, but there may also be small pieces of independent content that would not merit the title. It is convenient for the purposes of this article, however, not only to retain the term "companion" for its current product usage but also to allow it to signify any piece of content that makes a connection to an open-content article.
The creator of a companion also must define the nature of each connection: What happens when the user invokes the companion and what types of parameters, if any, are passed and returned in the invocation?
A companion may make multiple connections with an article, and multiple companions may be available simultaneously at any point. The most obvious companion for an online book is an online dictionary. In an open-content world, the reader should be able to point to an unfamiliar word and call up its definition instantly. Creating a context-specific dictionary is not yet a completely algorithmic process, but such a dictionary would be a more valuable companion than a mere generic overlay. A foreign word might be part of an idiom, and a companion dictionary of idioms may make a connection to the same part of the foreign-language text. Similarly, a grammar companion would very likely overlap with the companion dictionaries.
In general, therefore, when the user attempts to invoke a companion at a particular point, the user interface might first have to offer a menu to help the user choose, in the process showing, perhaps, to which portion of the underlying content (if any) each available companion relates. Users should be able to configure which companions they wish to include from time to time.
Where it is not obvious that companions are available, the user might ask to "Show Companions," say, so that some visible cue appeared in the article. For example, a "compass rose" symbol might be displayed wherever a chart (map) is available; or a DVD symbol might be displayed to show a film extract is available. In opening an article to companions, its owner also must decide what rights, if any, companions will have to manifest themselves in such ways. Multiple independent companions must either be compatible in their use of cues or, for example, the user may have to "Hide Companions" selectively in order to avoid conflicts.
There are circumstances in which the user might want a companion not merely to signal its availability but to be constantly present: The ultimate foreign-language help is a translation. The reader might call up the translation phrase by phrase, sentence by sentence, etc.it depends on how the source has been translatedbut the reader may prefer to have the whole translation automatically displayed, either en face or interpolated.
Articles of content may also be companions for each other, in which case the user should be able to navigate back and forth between them:
An audio companion could be linked to its foreign-language text to pronounce words or speak phrases and sentences. Users might also want to alternate listening to and reading successive segments, navigating between the text and audio.
Obviously, companions can also have their own companions. Not understanding something heard in a foreign-language audio book, the listener might call up the corresponding text; not understanding the text completely, the reader might then call up a translation of it; and so on.
And, of course, users should be able to produce their own companions using open-content tools; and it should also be possible for multiple users to attach suitable companions to a tabula rasa, such as an initially empty calendar, diary, or blog.
Now, imagine how open-content technology might change conventional publishing. Here are a couple of examples:
Children's books often include illustrations. At any time, other artists might also wish to produce illustrations, but these cannot be substituted into the books in print for obvious reasons. Were books to be published as open content using a computer-based device, however, other artists could offer to substitute their own illustrations.
Authors do not want their work tainted by poor illustrations, of course, and the best illustrators may refuse to illustrate works except on an exclusive basis. Degrees of "openness" are possible, however. At one extreme, a publisher may be completely open to third-party illustrations to allow the market to decide which ones are best. At the other extreme, the publisher may prefer to be closed to alternative illustrations (even while remaining open to other types of substitutions or additions, perhaps). In between these models, a publisher may accredit a limited number of "approved illustrators" from time to time.
For films, substitution and addition are already common practicefilms are dubbed into foreign languages, and subtitles are added for foreign viewers or the hearing impaired. Foreign-language versions may be judged to be not commercially viable for minority languages, such as Breton for example. For Breton speakers, and those interested in preserving the Breton language, however, there may be much more incentive to produce subtitles or a Breton soundtrack. If films were published in an open content form, then interested third parties could obtain permission to add their own subtitles or dialogue.
Currently, the soundtrack of a film would not be described as a "companion", of course. But once one conceives of all content as potentially open, articles like this are no longer an immutable fusion of their constituents but can be conceived as an ensemble of companions .
Since open-content technology enables connections between pieces of content, it could also be used to create new ensembles even when no third parties are involved. Here are a few examples:
A cookbook could have a video companion of the cooking techniques: Wherever the technique is called for in the text, the relevant video demonstration could be connected and invoked by the user if needed . There are many similar opportunities to attach video demonstrations to instruction and reference manuals. For example, how to train an espalier fruit tree in a pruning guide, how to change the head gasket in a car-maintenance manual, and so on.
Usually, opera lovers study the libretto before watching an opera because it is difficult to understand the words when they are sung (even for native speakers), and some of the language may be archaic. When a person is watching an opera on a computer-based device in the future, it should be possible to pause to refer to the libretto at the start of an aria or recitative. Vice-versa, it should also be possible to read a part of the libretto and then watch a performance of that part, repeatedly if desired.
During the radio broadcast of the BBC's "History of the World in 100 Objects" , the image of that part of the object corresponding to its audio description at that moment could be displayed automatically. Apart from describing objects such as historical artifacts, antiques, and works of art, there are many other uses for audio files with image companions attached that are more lightweight and, possibly, more suitable than videosonline lectures, virtual guided tours or product instruction manuals.
A companion invocation need not return content only; it can provide any sort of gadget:
As part of a cookbook ensemble, the user could invoke a companion to remember the list of ingredients of each recipe chosen for the coming week. On completion, the companion could return a shopping list for the chosen recipes.
Hopefully, sufficient interest will have been stirred by this short introduction to open content to bring other imaginations to bear upon its opportunities (and many outstanding questions). Like the magical command used in the title, maybe an open approach to content will unlock a cave of treasures .
3. Established authors and media firms can be ambivalent about the value of 'companions'. See for example Rowling v. RDR Books at http://cyberlaw.stanford.edu/case/rowling-v-rdr-books/
5. See, for example, http://www.patrickobrian.com/home.html/
9. The term "ensemble" implies bringing together content elements in a controlled environment to create a new article, cooperatively when more than one author or artist is involved. In contrast to some bootleg content, or mash-ups, it is not meant to imply that elements are altered significantly in the process.
10. The BBC recipes website: http://www.bbc.co.uk/food/recipes/ inserts hyperlinks to video demonstrations into its recipes. Using companion videos is an alternative and potentially less intrusive method of illustrating cooking techniques.
Martin McCaig taught computer science for several years. He spent most of his working life at Reuters, where he held a number of IT and marketing positions, including international marketing manager before retiring from there in 2002.
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