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Jose Stigliano, Marco Bruni, in
Encyclopedia of Information Systems, 2003 Hypertext is a system for linking related text documents that allows the participation of multiple
users. In a hypertext document, any word or phrase can be “hyperlinked” to information related to that word or phrase residing in the same document or in another document. When a hyperlink is activated, the hypertext system retrieves the related information. For example, by selecting a word in a sentence, the definition of that word is retrieved. Some hypertext systems allow users to see who has visited a certain document or link, or how often a link has been
followed, thus giving users a basic awareness of what other users are doing in the system. Another common multiuser feature in hypertext is the ability for any user to create links in documents authored by others so that the original author can become aware of new related material. The World Wide Web is a distributed hypertext information system based on the HyperText Markup Language (HTML), a standard language that describes the basic structure and layout of
hypertext documents called pages (HTML pages or Web pages). HTML pages typically contain links with addresses, in the form of uniform resource locators (URLs), of other Web pages that can be stored on the user's computer or on any other Web server in the world. Users of the Web “read” HTML pages with an application called a browser. HTML documents are “plaintext” files with tags describing structure and layout elements
embedded in the text. Tags are codes surrounded by angle brackets and usually paired (e.g., <h2> </h2, <p> </p>, and <table> </table>) that describe elements such as headers, paragraphs, and tables. To be readable by a browser, an HTML document must contain at least three pairs of tags, namely, <HTML> </HTML>, <Head> </Head>,
and <Body> </Body>, to indicate that it is a well-formed HTML document with a header and a body. The Web implements a simple and extremely powerful model of collaboration in which clients (Web browsers) request pages and web servers send the requested pages in response, using the Hyper Text Transfer Protocol (HTTP). Using simple text editors or word processors, users can create applications in the form of HTML
documents containing structured information; they can then post these documents on an intranet or the Internet, where they become instantly available to an unlimited number of users.End-User Computing Tools
IV.D. Hypertext
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Using information ethically, legally, and safely
LiLi Li, in Scholarly Information Discovery in the Networked Academic Learning Environment, 2014
HTTPS Everywhere (//www.eff.org/https-everywhere)
HTTP (Hypertext Transfer Protocol) is a familiar term to all when visiting different websites with URL addresses like “//www.google.com”. URLs are specific character strings used to indicate the web addresses of specific websites in cyberspace. In Chapter 3 we pointed out that HTTP is a telecommunication protocol used to transmit network information, while HTTPS (Hypertext Transfer Protocol Secure) is used for encrypted network communication. When asked about the differences between HTTP and HTTPS, Indian software engineer Naresh Kumar explained them to us in a simple way:
“Difference between HTTP and
1.URL begins with “//” in case of HTTP while the URL begins with “//” in case of HTTPS.
2.HTTP is unsecured while HTTPS is secured.
3.HTTP uses port 80 for communication while HTTPS uses port 443 for communication.
4.HTTP operates at Application Layer while HTTPS operates at Transport Layer.
5.No encryption is there in HTTP while HTTPS uses encryption.
6.No certificates required in HTTP while certificates required in HTTPS”
(Kumar, 2012)
As pointed out by Naresh Kumar in his blog, HTTP is the normal telecommunication protocol used to visit different websites. We know it is not secure because web hackers can easily intercept and monitor communication between a web client’s computer and a web server. To protect confidential information exchanged between a client’s computer and a web server, HTTPS should be used instead of HTTP. This is the reason many banks, e-commerce companies, email login webpages, online stock-trading companies, etc. use HTTPS for their intranets as well as the Internet:
■Bank of America (https://www.bankofamerica.com)
■MyGeorgiaSouthern.edu (https://my.georgiasouthern.edu/portal/myapps/login/myapps-login.php)
■Paypal.com (https://www.paypal.com)
■TDAmeritrade.com (https://www.tdameritrade.com)
With the rapid development of IT, it is now very easy to use HTTPS in the same way as HTTP. The Electronic Frontier Foundation (EFF; //www.eff.org/) is promoting HTTPS Everywhere (//www.eff.org/https-everywhere; Figure 8.4) and is making it available to online users worldwide with the objective of safeguarding their web privacy and web security in cyberspace. A non-profit organization, EFF has developed two versions of HTTPS Everywhere: one for Firefox (Version 3.0) and another for Chrome (Beta version). At the time this book is being written, different versions of HTTPS Everywhere for IE, Opera, Safari, and other web browsers are unfortunately still not available. If you would like to encrypt your web communications, then the sooner you install HTTPS Everywhere the better. Based on the author’s personal experience, installation is very easy. Just go to the HTTPS Everywhere website and click the image for “Install in Firefox” or the image for “Install in Chrome”. Then, follow the window instructions to install this add-on extension into your web browser. After installation, close your web browser and reopen it. Check the right upper corner of the menu bar of your web browser. You should see a new HTTPS Everywhere icon with a pull-down menu. Make sure that the EFF option in green is checked! You can enable or disable HTTPS Everywhere at any time you like.
Figure 8.4. Status of HTTPS Everywhere according to the pull-down menu
If you are using Firefox or Google Chrome you will see that the navigation toolbar within your web browser has changed. You will also see that the URL of Google.com has been changed from //www.google.com to //encrypted.google.com because your network connections with the web server of Google.com have been encrypted to prevent any eavesdropping. Although you have installed HTTPS Everywhere, you may still have to use HTTP to access some websites such as NationalGeographic.com or Yahoo.com as they offer only partial support of HTTPS communications. In this case, HTTPS Everywhere will display the warning given in Figure 8.5 if you click the little icon in front of any website URL that does not start with “//”.
Figure 8.5. Warning message from HTTPS Everywhere
Finally, HTTPS Everywhere is not computer software designed to avoid U.S. government surveillance. HTTPS Everywhere will not hide your real identity while you surf the net if the websites you intend to visit do not support HTTPS. Nor will it hide information about which websites you have visited or what you have downloaded or uploaded. This is the reason EFF (Figure 8.6) warns that “HTTPS Everywhere depends entirely on the security features of the individual web sites that you use; it activates those security features, but it can’t create them if they don’t already exist. If you use a site not supported by HTTPS Everywhere or a site that provides some information in an insecure way, HTTPS Everywhere can’t provide additional protection for your use of that site. Please remember to check that a particular site’s security is working to the level you expect before sending or receiving confidential information, including passwords” (EFF, 2013). For more detailed information about what HTTPS Everywhere can do and what it cannot do for you, read the HTTPS Everywhere FAQ section (//www.eff.org/https-everywhere/faq) carefully. Students preferring to use other web browsers such as IE, Opera, and Safari should seek other web applications to use HTTPS.
Figure 8.6. Homepage of Electronic Frontier Foundation
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The Internet and the Web
Stuart Ferguson, Rodney Hebels, in Computers for Librarians (Third Edition), 2003
Hypertext, HTTP and HTML
Since hypertext is an important component in the Web, it is worth pausing to consider the difference between an information resource that uses hypertext in its publication and one that is published in the ‘traditional’ way. The use of the word ‘pausing’ betrays the fact that the authors are steeped in traditional forms of writing, because they are saying, ‘right, before we discuss the Web, we're going to have to digress and discuss hypertext.’ Hypertext writers, on the other hand, would present a section or chunk of information (called a node) about the Web and a separate node on hypertext. Since the publication is intended to be a learning resource, they would create a link between the two nodes, so that readers who are unfamiliar with the concept of hypertext could follow a link from the node on the Web to the one on hypertext, and read up about it. The link between the nodes would be made apparent to the reader by highlighting the term ‘hypertext’ in the node about the Web and could be selected by the reader by pointing to the term and indicating the selection to the computer system. The node on hypertext would, in turn, have links, for example, one back to the node on the Web and another to a third node that discusses the computer pointing device used to select links (typically a mouse; not discussed until Chapter 6 of this book).
Figure 1.4. The web-like nature of hypertext
One way of distinguishing between traditional printed text and hypertext is to think of text that is presented in linear and non-linear sequences. Traditional text is written in a linear sequence and the reader is more or less confined to following that sequence. A book such as this one, for example, is generally read in a linear sequence, starting at the Preface and finishing with the final chapter, or perhaps appendices (or index in the case of conscientious reviewers). The reader may be directed to other sections of text (for example, the reference to another chapter at the end of the last paragraph) or even to another text altogether (for example, the earlier reference, ‘Bruce 2002, p. 9’), but these references tend to be of an incidental nature. Hypertext, on the other hand, encourages the reader to follow links to other nodes. Typically these nodes express a single idea or concept, for example, an entry in an encyclopedia would constitute a node and might present a variety of links for the reader to follow.
Hypertext has been combined with multimedia (itself a combination of traditionally separate media, such as graphics, sound and video) to create hypermedia, which allows users to follow associative links, not just to other nodes of text, but also to other media presentations, such as sound and video, for example, an encyclopedia entry on kookaburras could provide a link to a node storing an image illustrating the bird and another to a sound recording of the its distinct laughing call.
The Web has its origins in a hypertext publishing project at CERN (the European Particle Physics Laboratory) in Switzerland. In Web publishing, the nodes or chunks of text, referred to earlier, are called pages or web pages. Each page contains links to other pages within the publication, similar conceptually to the reference earlier to Chapter 6. Each page may also contain links to publications elsewhere on the Web, similar to the Bruce reference earlier, which referred the reader to a book by another author. In practice, of course, the reader of a print-based resource may have difficulty retrieving the actual resource to which reference was made, whereas a reader who is presented with a hypertext link, or hyperlink, on a web page can actually follow the link and access the second publication electronically (all being well). Readers of a Web version of this chapter, for example, could follow links to those Web-based resources referred to in the course of the chapter, even though they are stored at completely different websites in a variety of countries.
For documents to be mounted on the Web, there needs to be a standard for their publication. One standard, central to the Web, is HTTP (HyperText Transfer Protocol), which, as the name suggests, is the protocol (the set of rules or conventions) used to move copies of hypertext files between Web servers and Web clients. It is a communications protocol, like Telnet (discussed earlier), and will be discussed in Chapter 7.
The other principal standard associated with Web publication is HTML (HyperText Markup Language), which is a code that is used to determine the format of Web pages and to embed links to other pages/publications in specified text. The use of the HTML standard means that when someone uses an HTTP client to download a publication from an HTTP server, the client is able to identify the various parts of the document and present them to the user correctly. Each element in a page (such as title, heading, paragraph, picture or textual link) is marked with an HTML tag, which carries instructions about what is to be done with the tagged element, for example, highlighting of text with embedded links. Each element will be flanked on either side by an HTML tag so, to take an example, the title of this work as it appears on the publisher's website will be preceded by certain HTML tags indicating how it is to be presented (for instance, font style) and followed by another tag indicating that the previous instruction has ceased to apply. To take the example of font colour, the tags and element might look like this:
<font color=“#FF9933”>Computers for librarians</font>
Each tag is enclosed in the ‘<>’ symbols. The diagonal slash in the second of the two tags indicates that this particular instruction ends here, and is a common piece of HTML practice. Note, too, that this instruction relates solely to font colour, and there will be other pairs of tags dealing with other aspects of the presentation of this particular element, title, such as the actual font style.
The original HTML format and tags were created by Tim Berners-Lee when he developed the HTTP protocol. They were an application of an earlier, and much more complex, markup language called SGML or Standard Generalized Markup Language. As the simple example above demonstrates, a markup language specifies characteristics of electronic text such as the font style and layout of a data element. Prior to the use of generalised tags, specific electronic documents would have been marked up by publishers for output in the required formats and styles. Interest in generalised languages began in the late 1960s and resulted first in GML (Generalized Markup Language) and then SGML, first published as a working draft in 1980 and by 1986 an international standard: ISO 8879:1986 (SGML Users’ Group 1990). Because it is independent of specific computer systems and non-proprietary – and because it is extremely comprehensive language – SGML has become a very widely adopted standard. (The ISO is the International Standards Organisation, which is a major source of many of the protocols used by the library and information sector.)
The downside of SGML's comprehensiveness is that it is extremely complex. It uses a range of what are called Document Type Definitions (DTDs) to define the tags and syntax used for individual formats, such as journal articles, architectural drawings or novels. DTDs are sets of rules that define the elements that make up a document and encode them in such a way that text within the document can be retrieved, displayed and exchanged across different platforms (in other words, irrespective of the user's computer hardware/system software). Encoded Archival Description Document Type Definition (or EAD DTD), for instance, was developed specifically to designate the intellectual and physical elements of archival finding aids.
HTML is essentially an application – in other words, a DTD – of SGML. One of its strengths is its simplicity compared to a language like SGML (a benefit that library web developers can appreciate). That simplicity can also be a disadvantage, and it can be used for purposes for which it was not designed. As new features are added by web designers it becomes less of a standard, and some users’ web browsers (see below) may be unable to cope with the developments. Different varieties of HTML have begun to emerge, which poses the danger that it could become ‘a series of proprietary formats’ (Deegan & Tanner, 2002, p. 125), and thus cease to be a standard.
XML (Extensible Markup Language) is another important standard, a subset of SGML specifically developed for use with the Web. It was developed under the auspices of the World Wide Web Consortium (or W3C): a grouping of vendor-neutral organisations which recommends to members the standards and protocols that underlie the Web. It has been designed as the universal format for the exchange of structured documents and data on the Web. The intention was that XML would enable SGML to ‘be served, received, and processed on the Web in the way that is now possible with HTML’ and that HTML itself would become an XML application, as distinct from an SGML one. Its primary purpose is ‘as an electronic publishing and data interchange format’:
XML is primarily intended to meet the requirements of large-scale Web content providers for industry-specific markup, vendor-neutral data exchange, media-independent publishing, one-on-one marketing, workflow management in collaborative authoring environments, and the processing of Web documents by intelligent clients. It is also expected to find use in certain metadata applications (Cover Pages 2003).
Because of the insistence on using the Unicode character set (see Chapter 6), XML can be used for the publishing of Asian and European languages, so it is very much an international standard.
It is sometimes suggested that XML might replace HTML, for instance, in the area of professional web development (see, for example, Kochtanek & Matthews 2002, p. 105), but it is worth being aware of the development of XHTML, a version of HTML that is based on XML and not SGML, and which is intended to provide some of the advantages of both markup languages.
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XML (Extensible Markup Language)
Joseph C. Otto, in Encyclopedia of Information Systems, 2003
I.B. Relationship to HTML and SGML
Hypertext markup language (HTML) is the most frequently used language on the Internet, and probably will be for a while. It has insertable code, or tags, that are fixed, or static–they cannot be changed. The display of the Web site is completely dependent upon the translation of the codes by the browser. The browser is the software used to translate the information of the Web site for display back to the user. HTML creates a very simple type of report-style document. The biggest limitation of HTML is that it allows only one way of describing the content of a Web site. The number of elements allowed is limited, whereas with XML, the elements are defined by the user, and are unlimited.
XML is not fixed; it is not dependent upon the browser, but instead translated by the definitions used by the applications or the stylesheets. The applications or stylesheets are separate from the content and control how the content is defined or displayed. It allows the creators of Web sites to set up their own customized markup applications, allowing the exchange of information within their own particular domain.
XML does not define, nor is it limited to, generic tags; instead it is the creator that sets up the tags needed in the document. Instead of trying to work within the limitations of HTML, the user can create their own tags with XML. This results in smarter documents, documents that can be used, manipulated, and browsed more efficiently.
XML is a small subset of SGML, written in SGML. SGML, standard generalized markup language, is the international standard metalanguage for defining the descriptions of how different types of documents are organized and for setting up Web sites. It is the mother language–a very large, powerful, and complex markup language that has been used in industrial and commercial areas for years. SGML is considered to be overly complex and too large for most common applications, therefore not appropriate for most Web site creations.
XML is an easy-to-use, “watered-down” form of the more complex SGML. XML is designed to make it easier to create and define documents, easier to transmit, and easier to create interoperable documents than possible with both SGML and HTML. Interoperable documents can be transferred between computers, no matter what type of operating system, browser, platform, or application. XML allows users to define their own document types and also to make it easier to write programs that can manipulate the created documents.
XML is closer to being an abbreviated version of SGML than an enhanced version of HTML.
XML is not meant to replace HTML. HTML will be around for a very long time to come. XML is an alternative that allows the user to define their own markup tags, allowing for more flexibility when describing the documents or data. You do not have to know HTML or SGML to learn XML but it can be useful because the syntax and terminology are similar.
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Generic data management software
Stuart Ferguson, Rodney Hebels, in Computers for Librarians (Third Edition), 2003
Hypertext
Hypertext has already been mentioned as a special form of text retrieval solution that makes it possible for users to navigate between sections of an electronic information resource or between separate resources, using links embedded in them. In Chapter 1 it was introduced as an important component in the World Wide Web, providing means of web publication (HyperText Markup Language or HTML) and retrieval (HyperText Transfer Protocol or HTTP). Examples of applications that may be used in the library environment include:
•electronic encyclopedias, which allow the user to follow associative trails from one chunk of text to another or to access other media (for example, graphics or sound)
•computer-assisted instruction packages, which encourage self-paced learning, again by encouraging users to follow associative links (for example, to background information)
•full-text legal resources that allow users to follow links to relevant statutes, case reports or definitions of legal terms
•library guides, giving general information, physical layout of buildings, information about collections and so on.
Some of the packages used to develop library applications use a notecard or notepad analogy to suggest what they do. From the user's point of view, the hypertext-based system presents screens of information which may recall the five-by-three index card. These cards, or pages in the case of the Web, are referred to as nodes. A node often represents a single concept, such as an encyclopedic entry or a legal definition. Note that, although the focus here is on hypertext, there are hypermedia applications, in which case a node might not be a chunk of text but a piece of music (for example, in an electronic encyclopedia), a graphic (for example, a floor plan in a library guide) or a video clip (for example, someone speaking).
Each node is linked to other nodes on the database and the user is encouraged to follow associative links: for example, by selecting highlighted text or by selecting a ‘button’, which is an icon on the screen representing a particular option or procedure. Where an author intends two nodes to be viewed sequentially, there will be a link between the two. In some applications, the network of interrelated nodes is called a stack. The stack is a matrix of nodes, through which the user can follow an associative trail.
How does the user access and browse this matrix of information? There are basically three techniques:
•follow the associative links between nodes: that is, follow the explicit links created by the author of the hypertext resource
•search across the stack for keywords, as one would search an database management system or text retrieval system
•use a browser, which represents graphically the position of a particular node in the stack.
The browser is an attempt to overcome one of the problems associated with use of a hypertext system, namely, that a user can become disorientated and lost (‘cognitive overhead’ is one expression used to describe this phenomenon). A browser is a form of mapping device, which typically presents the user with a graphical representation of where the current node is in relation to other nodes. Another tool for helping users navigate through the matrix of nodes is an audit trail, which allows them to backtrack to previous nodes of information. In large hypertext-based resources, however, audit trails may become too long to be of much help to users. In this case, they may have to rely on browsers, although it is worth pointing out the problems of representing nodes within a particularly large resource, given the size of most computer screens.
In some hypertext applications, it may be desirable for the user to be able to create new nodes and develop new links: in effect to annotate hypertext documents. This might be a useful feature in a personal information management system, although not perhaps in a library package.
Hypertext is generally associated with the so-called graphical user interface. User interfaces are discussed at the end of the next chapter, but it is worth noting, in this context, the importance of the interface, that is, the combination of computer hardware and software that allows the user to maintain a dialogue with the computer system. Features of the graphical user interface that are of particular relevance are:
•windows: a single screen will present the user with one node of information, but the use of windows enables the user to open more than one window on the screen, each window displaying a different node
•icons, which are graphical representations of nodes, options or commands and which present users with a choice of actions
•pointing devices, such as ‘mice’, that allow users to move a pointer on the computer screen and to select actions represented by icons or by highlighted text within the current node.
User interfaces are discussed in more detail in Chapter 6.
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Data, Results, and Discussion
Mary K. Bolin, in The 21st Century Academic Library, 2018
Intertextuality
Hypertext is clearly very intertextual. Not only are websites literally linked together by portions of text on each page, the information on the pages is expected to conform and agree with information on other pages (e.g., about what branch libraries exist, what borrowing rules are, what relationship to the university is necessary for using the library). Websites are a crucial part of the library’s intertext (Lemke, 1995), the network of texts that is used and recognized by any discourse community. The websites use the language, mental models, and texts of library services in presenting the home page and the pages that link to it.
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MEET THE WEB
Ian H. Witten, ... Teresa Numerico, in Web Dragons, 2007
XML: EXTENSIBLE MARKUP LANGUAGE
HTML describes the visual form of web documents, not their content. The M is for markup, which applies to the format—just as copyeditors mark up manuscripts in traditional publishing. This emphasis on visual aspects contrasts with database representations, which are rich in expressing content in terms of well-structured data records but impoverished in expressing presentation.
Database records are interpreted with respect to a schema, which gives a complete definition of the fields that constitute each record. Personal records, for example, contain separate fields (first and last names, birth data, address, and so on), some of which—such as “birth data” and “address”—are themselves structured into further fields. This kind of organization makes it possible to answer complex queries, because meanings are attached to each field of the record. Whereas databases were conceived for automatic processing and born in computers, documents were conceived for human communication. Documents are difficult to process automatically simply because it is hard to interpret natural language automatically. The schema is the key to interpreting database records, but no corresponding semantic description is available for documents.
The Extensible Markup Language, XML, is a systematic way of formulating semantic document descriptions. It's neither a replacement for HTML nor an evolution of it. Whereas HTML was designed to display information, XML focuses on describing the content. It's a declarative language: it doesn't actually do anything. Figure 3.2 shows a note that the CatVIP club sent to Felix begging him to stop pacing back and forth across the screen, expressed in XML.
Figure 3.2. Representation of a message in XML.
When interpreted by a web browser, the HTML in Figure 3.1(a) produces the web page in Figure 3.1(b). In contrast, the XML in Figure 3.2 produces … nothing. It focuses on content, not presentation. There's a message header (<heading> … </heading>) and a body (<body> … </body>), preceded by some auxiliary information using other tags (<date>, <day>, etc.). Unlike HTML, XML tags are not predefined—you make them up as you go along. The assumption is that you choose them to provide a useful semantic description.
The whole note is embraced within a <note> tag. Attributes can accompany tags (as with HTML), and this note has the identifier B110 as an attribute, which could be used to refer to it. Another way of specifying the date would be to make it an attribute too, like
The advantage of using separate elements, as Figure 3.2 does, is that it's more suitable for computer interpretation, just like database records.
In addition to the date, the description in Figure 3.2 also specifies the sender and the receiver. Of course, these could be further decomposed into subfields if appropriate. The body is the truly textual part, which is typically unstructured. As this simple example shows, XML yields semi-structured representations that lie somewhere between database schema and free text.
XML documents have a hierarchical organization. A collection of notes like the one in Figure 3.2 could be framed within an enclosing <messages> … </messages> construct, so that individual notes were identifiable by their id attribute. It is possible to define a formal schema—like a database schema—that precisely expresses constraints on the structure of the document in terms of the elements and their nesting, and the attributes that can occur with each element. Furthermore, elements are extensible. We could later decide to add a new item <weather> … </weather> to the note, indicating whether it was written on a sunny or a cloudy day.
XML offers new opportunities for document processing by exploiting the semantics associated with the tags. Everyone is free to define his or her own tags, and only the page author (or the author of the corresponding XML schema) knows what they are supposed to mean. XML doesn't help others to understand the meaning of the tags. In Chapter 4, we'll see that the semantic web, another creation of Tim Berners-Lee's fertile mind, is moving in the direction of removing this obstacle too.
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What does the digital do to knowledge making?
Bill Cope, Mary Kalantzis, in Towards a Semantic Web, 2011
The hype in hypertext
Hypertext represents a new, non-linear form of writing and reading, it is said, in which readers are engaged as never before as active creators of meaning (Chartier 2001).
However, even at first glance, hypermedia technologies are not so novel, tellingly using metaphorical devices drawn from the textual practices of the book such as ‘browsing’, ‘bookmarking’, ‘pages’ and ‘index’. Moreover, when we examine the book as an information architecture, its characteristic devices are nothing if not hypertextual. Gutenberg’s Bible had no title page, no contents page, no pagination, no index. In this sense, it was a truly linear text. However, within half a century of Gutenberg’s invention, the modern information architecture of the book had been developed, including regularly numbered pages, punctuation marks, section breaks, running heads, indexes and cross-referencing. Among all these, pagination was perhaps the most crucial functional tool (Eisenstein 1979).
The idea that books are linear and digital text is multilateral is based on the assumption that readers of books necessarily read in a linear way. In fact, the devices of contents, indexing and referencing were designed precisely for alternative lateral readings, hypertextual readings, if you like. This is particularly the case for knowledge texts rather than novels, for instance. And the idea that the book or a journal article is a text with a neat beginning and a neat end—unlike the internet, which is an endless, seamless web of cross-linkages—is to judge the book by its covers or the journal article by its tangible beginning and end. However, a book or a journal article sits in a precise place in the world of other books, either literally when shelved in a library, and located in multiple ways by sophisticated subject cataloguing systems, or more profoundly in the form of the apparatuses of attribution (referencing) and subject definition (contents and indexes).
As for hypertext links that point beyond a particular text, all they do is what citation has always done. The footnote developed as a means of linking a text back to its precise sources, and directing a reader forward to a more detailed elaboration (Grafton 1997). The only difference between the footnote and hypertext is that in the past you had to go to the library to follow through on a reference. This relationship to other writing and other books comes to be regulated in the modern world of private property by the laws, conventions and ethics of copyright, plagiarism, quotation, citation, attribution and fair use (Cope 2001b).
Certainly, some things are different about the internet in this regard. Clicking a hypertext link is faster and easier than leafing through cross-referenced pages or dashing to the library to find a reference. But this difference is a matter of degree, not a qualitative difference. For all the hype in hypertext, it only does what printed books and journal articles have always done, which is to point to connections across and outside a particular text.
These are some of the deeply hypertextual processes by which a body of knowledge has historically been formed, none of which change with the addition of hypertext as a technology of interconnection. From an intertextual point of view, books and journal articles are interlinked through referencing conventions (such as citation), bibliographical practices (such as library cataloguing), and the inherent and often implicitly intertextual nature of all text (there is always some influence, conscious or unconscious, something that refracted from other works notwithstanding the authorial conceit of originality). From an extratextual point of view, books and journal articles always have semantic and social reference points. Semantically, they direct our attention to an external world. This external reference is the basis of validity and truth propositions, such as a pointer to an authentic historical source, or a scientifically established semantic reality located in a controlled vocabulary, such as C = carbon. The subject classification systems historically developed by librarians attempt to add structure and consistency to extratextual semantic reference. From an extratextual point of view, texts also have an acknowledged or unacknowledged ontogenesis—the world of supporters, informers, helpers, co-authors, editors and publishers that comprises the social-constructivist domain of authorship and publishing. Not to mention those at times capricious readers—texts enter this social world not as authorial edict, but open to alternative reading paths, in which communicative effects constructed as much by readerly as they are by authorial agendas.
To move on now to things that, in some important respects, are genuinely new to the emerging digital media.
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Digital history, archives, and curating digital cultural heritage
Arjun Sabharwal, in Digital Curation in the Digital Humanities, 2015
Historical hypertext
Ayers (1999) writes about historical hypertext, “Hypertextual history promises to be a tool that lets us think more rigorously. We might be able to imagine ways to write that let us deal more effectively with multiple sequences, multiple voices, multiple outcomes, multiple implications” (para. 18). In the “Interchange” roundtable (Cohen et al., 2008), Thomas addresses the hypertextual capabilities of the emerging digital technologies, which offer readers multiple ways to navigate historical texts by following preferred pathways through the Web of hyperlinked texts. This is very different from reading linear texts of works in print formats commonly found in archived manuscript collections, with which historians are familiar. However, not all historical texts or media require hypertextual rendering, but including such documents in a Web presentation will enhance contextualization of digitally processed texts and media. It is also possible to transcribe series of related historical texts—such as correspondence, diaries, memoranda, newspaper clippings—and present them in hypertext format for improved navigation. The information architecture of such Web sites must completely support the thematic structure of such sites therefore.
Historical hypertext may well have roots in the Memex project of Vannevar Bush, Director of the Office of Scientific Research and Development in the Library of Congress, who had envisioned the use of computing using the Memex program by historians accessing historical information through small-scale high-quality microfilms located inside the unit, which was a highly sophisticated desktop user interface with controls to access media. The Memex breaks away from the model of ontologically structured data (common in library catalogs) requiring researchers to navigate the classification system’s classes and subclasses, and reinforces mental associations, which, in Bush’s view, demonstrates how the human mind works (Bush, 1945). In the case of history, such associations among people, events, locations, dates, and various social, political, and economical contexts are the backbone of the Memex. Bush writes,
The historian, with a vast chronological account of a people, parallels it with a skip trail [or paths], which stops only on the salient items, and can follow at any time contemporary trails which lead him all over civilization at a particular epoch. There is a new profession of trail blazers, those who find delight in the task of establishing useful trails through the enormous mass of the common record.
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Bernstein (1999) demonstrates further that hypertextuality had already been present in the linear forms of historical narratives even as early as the fifth century BCE when Herodotus wrote Histories. Constructing the linear historical texts known to generations of historians antedating the arrival of computers, thus, did not require hyperlinks common in Web sites; according to Bernstein, the reader’s mind shapes those paths based on associations that readers establish during reading. Definitions, clarifications, references, linkages to other events (covered in more or less detail than those in the main narrative) already provide a structural framework for historical hypertext, enabling researchers to put the text aside, consult references, and verify names, locations, and dates. Such diversions should be voluntary on the readers’ end; however, skeptics may view such hyperlinks as prescriptive and programmatic as to instruct readers where to wander away from the main narrative. The associations that Bush writes about are subjective in nature; all hyperlinks can communicate is the availability of related texts at specific points throughout the texts. Virtual museums, exhibitions, and history Web sites fit this model best as long as their information architecture supports spontaneous and subjective reading.
TEI-encoded historical texts represent another significant category of historical hypertext that is both human- and machine-readable. In contrast to manually designed Web sites, TEI documents feature tagged data corresponding to specific taxonomies such as name and subject authorities, geographical names, and document and file types in an XML database. This allows project teams to link documents to indefinite sets of TEI documents featuring the same tags. A Web archive of transcripts from multiple archives can utilize such a method because they can also share the same database. TEI coding can also improve oral history transcriptions with important geographical locations, organization names, personal names, events, and other data. The tags are intentionally prescriptive as multiple documents may use a shared index to enhance navigating considerably larger corpora of historical texts, but will not prevent readers to divert away from the hypertext as they like, which is what Bernstein is demonstrating. TEI projects also represent some of the earlier digital humanities data curation initiatives in archives and libraries participating in TEI projects.
Preserving TEI projects will also present challenges for archivists not familiar with the schema and database structure. Although it appears that the full text has been tagged with key tag elements of the system, digital curators must ensure the long-term preservation of not just the full text but the database and its structure and relationship of the vocabularies (or ontologies) used in the text.
Information architecture, hypertextuality, and cybertext—all discussed at length in the next chapter—have significant implications for digital historiography and historical hypertext, and it may not be too far-fetched to classify such corpora of texts as ergodic literature (Aarseth, 1997). Today’s historians will plow through large numbers of primary and secondary sources in print and digital form to locate answers for historiographical questions, and research is well past any trivial reading activity. In fact, in digital historiography, researchers will navigate multiple cybertexts—as Bernstein (1999) illustrates—and rely on writing skills to represent the past through digital sources. Digital historiography, nonlinearity, hypertext, and the experience with ergodic literature represent a continuity of research process from earlier, predigital times in human history.
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A practical framework for medical device interoperability conformity testing (IHE PCD and IHE DEV Domain)
Elliot B. Sloane, in Clinical Engineering Handbook (Second Edition), 2020
PCD ACM AC actor interface variables
The WCTP HTTP host or IP address and port number of the AC actor needs to be able to be modified and display the configuration of the HTTP connection over which PCD-06 messages will be sent to the AC.
The configuration information of the HTTP transport for the PCD-07 response message is contained within the PCD-07 message and is not to be configurable for the AC actor.
The AM-AC WCTP HTTP transport needs to be configurable for secured (HTTPS/SSL) or unsecured (HTTP) communications requests and responses.
In support of group sending actor testing the AC actor needs the ability to simulate endpoint communication devices so that each of them can independently autorespond in a configured manner (ignore, read receipt, and accept/reject) without requiring manual operator intervention for each PCD-06 message sent to each of the endpoint communication devices.
The AC should be capable of both synchronous (polled) or asynchronous (push) status updates based on requests from the AM.
The AM-AC WCTP MCR support and corresponding wctp-VersionQuery response needs to be configurable for the AC to signal MCR support indications to the AM.
Endpoint communication device type needs to be configurable on a per device basis to behave as a one-way (fire and forget), 1.5-way (delivery confirmation only), or true two-way (full status updates and responses) device (Table 15).
Table 15. Variable mapping: PCD ACM AC actor.
| WCTP Server URL | //10.0.0.1:2575/wctp/wctp.dll |
| WCTP wctp-Originator senderID | ACMAMVENDOR |
| WCTP wctp-Originator securityCode | pswd |
| WCTP wctp-VersionResponse version Indicating whether or not response is supported and if so to indicate what WCTP version—1.1 (no MCR), 1.2 (unpaired MCR), or 1.3 (paired MCR) | unsupported wctp-dtd-v1r1 wctp-dtd-v1r2 wctp-dtd-v1r3 |
| WCTP wctp-Recipient recipientID | 1234 555-1234 555-555-1234 |
| Boolean (operational mode) | true false |
| Empty (no auto reply) or list of Delivered or Not Delivered, Read or Ignored, and Accepted or Rejected | Delivered Not Delivered Read Ignored Accepted Rejected |
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