Using OII Document and Multimedia Standards in Concretizing the Virtual Learning Environment


Anne Karjalainen

document analyst, Jyväskylä University, Information Technology Research Institute

student(?) of Jyväskylä University, Programme of Information Technology, Digital Media

P.O. Box 35, SF- 40351 Jyväskylä, Finland




Abstract. In this paper we present the main principles of OII and other important information standards, and shortly discuss the possibility to benefit from them in the numberous conversions attacher to the publishing process Distance Learning material. We also represent the main categories of the OII and related standards. The Open Information Interchange (OII) is an iniative within European Comission’ s IMPACT 2 to promote improved awareness and use of media-independent information coding standards for the exchange of information in electronic form.

Keywords: Standards, open information interchange (OII), distance-learning material



1 Research of the Distance Learning Materials in Etäkamu- Project

In TheEtäkamu- project the research conserning the Distance Learning material and the conversions has been the essential part of the research so far. In 1996 the Material research group published a wide-area report of the subject [ Karjalainen, Komu, Multisilta and Urponen, 1996] . The report delt with representing and converting the multimedia material, such as video, sound, text, animation and pictures. The basic idea laying behind the report was to discuss the conversions of different kind of multimedia objects to the file formats accepted by the most Internet browsers. The text was presumed to be presented in a HTML-hypertext format [ W3 Org., 1996] .

On 1996 and 1997 the attention was paid to the logical structure of the Distance Learning material [ Karjalainen, 1997A; Karjalainen and Mäkitalo, 1996; Karjalainen 1997 B] . Part of the research was carried out in co-operation with the Pedacogical research group of Etäkamu- project. Within the research the didactically sound logical structure for Distance Learning material was developed, documented and modelled, and revised. The logical model has been referred as the Structure Model for Distance Learning Material. The basis of the model lies on the Educational Technology’s process model for creating the Distance Learning material, the logical, internal structure of the material, and educational conversation principles represented by Holmberg [ Holmberg, 1989; Holmberg, 1992] , and on the congnitive and modern behavioral theories of learning represented by [ Korhonen and Väliharju, 1995; Ruokamo-Saari, 1995; Holmberg, 1992] .

The basic tecnical architectures and tehcnical solutions for hypermedia-based learning environment were also discussed from the viewpoint of using relational (or object-oriented) databases, C++-programming language and Java [ Nykänen and Ala-Rantala, 1997] . Also software-tool -specific and russian language charset-spesific research led to the reports of Materials research group [ Lehto, 1997A; Lehto 1997B] .

Different views of using the database structures or document standard markup languages as a saving and searching form of the material have been discussed throughout the research process. Furthermore, the question of the suitable representation format on the WWW has been arisen from time to time. The premiss of representing the Distance Learning material as a HTML-language [ W3 Org., 1996] standard format shall be reviewed and repositioned again as the standardization process of the XML-language[ Cover, 1997] continues.

As it is said that "behind every successful man stands a woman" it can be recognized that behind the research process considering the Distance Learning material there have been standard formats for multimedia and document objects. There have as well been standard query languages and the possibility to use them for querying the relational or object-oriented databases. So far we haven’t been paying so much attention to the standards themselves, but to the available formats. It is time to rise up the curtain and reveal the "woman" standing behind our researc, and time to talk about the standards themselves. To reveal the true nature of this "backstage phenomenon", we discuss the OII and related standards, what they are, and how can we benefit from knowing them.


2 Open Information Interchange Standards and Standards Related to It

Open Information Interchange in an iniative within the European Comission IMPACT 2 programme. The purpose of the OII is to promote improved awareness and use of information coding standards for the exchange of information in electronic form. The activities of OII continue under INFO 2000, a new programme proposed by the European Comission for stimulating the Development of the European multimedia content industry[ Tucker, 1996] .

In order to stand the test of time, information must be encoded in widely supported standard representations and formats. Therefore the information produced is to be of maximum use and to maintain its value. Appropriate standards exist and others are nearing completion for representations and formats that will meet most needs. [ Tucker, 1996] .


2.1 What Is a Standard - and What Do We Need Standards For?

The word standard imply consistency and conformity and, in the world of computing and telecommunications, facilitate interoperability and compatibility. Yet we don’t pay so much attention to the standards and their use. There is a general agreement that standards are necessary and inherently a "good thing". More often than noticing the use of standards we rise to be aware of the standards in a situation of their absence [ Mac Morrow, 1993] .

The consequences of an absence of standards is perhaps most easily seen in the area of electricity supply. For example, a hair drier manufactured in the UK requires a three pin plug, and it cannot be "plugged in" to an electrical socket everywhere in the world, only in countries that have a three pin plug socket also (this is not the case for example in Finland, where the socket has only two pins). Even if a suitable adapter for the actual socket elsewhere could be found, the appliance might not still work because the voltage varies in different part of the world. This simple example illustrates the problem of a lack of standards - a failure to connect and harness the power of the machine [ MacMorrow, 1993] .

To support complex "knowledgeable" forms of information, the information infrastructure needs a full architecture, in other words both supporting structures and specialized data formats. These structures and formats must be realized in standard interfaces and in the standard objects being interhcanged (for example sound, video, files, e-mail, picture and so on). An essential technical aspect of the information needed for open interchange is interoperability. The interchanged information must have the capacity to be directly compatible with applications and their components so that it can be interpreted and used directly to accomplish tasks. The key to the interchange of structured and interoperable information is the development of global standards [ Tucker, 1996] .

Two kinds of standards can be found. There are international standards (de jure) accepted by the International Standards Organization ISO. These standards have their own ISO-specification number to be referenced. For example, the SGML (Standard Generalized Markup Language) is a ISO-8879:1986 standard, accepted on 1986[ Travis and Waldt, 1996, 488; Goldfarb, 1990] . All well-known specifications are not standards accepted by ISO, but because of their widespred nature and acceptance can be referred as de facto standards. Both of them are being discussed within the OII standards.


2.2 OII Standards and Standards Related to It

Tucker [ 1996] divides the stadards into the several grops by the nature of the standards. In the figure 1 we have illustrated the main groups of standards by his grouping.

Figure 1: Main groups and subgoups of OII standards


In the figure 1 the OII standards have been grouped into four main categories, which are: Information Encoding Standards, Document Standards, Multimedia Standards and Other Important Information Standards. Main categories are illustrated with a dark-coloured boxes. The subcategories, or the most influential standards of the main category have been named or grouped in the white boxes laying under the dark-coloured boxes. On chapter 2.3 we introduce these groups of standards more closely, and also describe the nature of these groups by representing some of the standars as an examples of their category.


2.3 Information Encoding Standards

These standards can be represented as groups of standards dealing with the graphical data interchange, compression standards and characters and character codes. First we talk about graphical data interchange formats, and then briefly about the compression standards and the characters and character code standards.


2.3.1 Graphics Interchange Formats

The graphics interchange formats are being discussed by the ideas and principles represented by [ Mumford, 1996] .

The main reasons for exchanging the graphical data are: providing the intermediate storage for modelling information, transmission of graphics into the output devices (suitable formats for this would be TIFF or PostScript), transmissions between the applications (CGM), and allowing cut and paste operations.

The conseptual and terminological framework of graphics standards is a Computer Graphics Reference Model (CGRM), ISO 11072 developed by the the community working in graphics. Usually two basic differences of the representation of graphics can be found: the bitmap (or rasterized) pictures, and vector graphics. The main difference is that the vector graphics are scalable, but require a lot of storage space if the objects that are to be presented are of a complex form.

File formats generally have two aspects to their definition, which may be explicit in their definition or may just be implicit. The first aspect is specification. File can, for example, allow circles, polylines and ellipses to be included and that their definition in the file format involves the storage of certain aspects, such as the radius of a circle, and particular attributes such as line color. The second aspect is to how the information is actually stored on a computer system. That is the purpose of encoding. The CGM standard (Computer Craphics Metafile) provides a good example of the different requirements for encoding of file formats. To address different requirements CGM defines three encodings, for character, binary and clear text encodings.

The CGM (Computer Graphics Metafile) is also the international standard for storage and exchange of 2D graphical data. The term metafile is used in computer graphics to denote a mechanism for storing and transmitting graphical information in a device independent way. The CGM standard specifies which elements are allowed to occur in which positions of a metafile.

Proprietary standards for graphic interchange are, for example TIFF (Tagged Image File Format, de facto standard), GIF (Graphic Interchange Format, de facto standard), and PNG (Portable Network Graphics, format designed to be a successor to GIF) of rasterized, bitmap pictures. HP-GL is (Hewlett-Packard Graphics Language) a de facto standard for vector graphics developed by HP. The use of graphical file formats between applications and machines is not a very simple issue, and many of the users notice that the graphics "doesn’t work". There may be several reasons for this, such as:

the software may have implemented the specification incorrectly

the format specification may be ambiguous and open to different interpretations

the generating software and the interpretating software may have implemented different subsets of the format specifications and thus some parts of the file may not be understood on the interpretation


2.3.2 Compression Standards and Characters and Character Codes

In this chapter the compression standards are being briefly discussed according to[ Garcia, Yeadon and Hutchison, 1996] , and the characters and character codes according to [ McGregor Ross, 1996] .

The use of graphics, video and audio is increasing the amount of data that needs to be stored, interchanged, processed, and presented by computers. New applications such as video conferencing, video-on-demand and distance learning are putting increasingly greater demands on electronics and telecommunication equipment.

The compression can be made by exploiting the compression techniques, such as truncation, interpolative techniques, predictive techniques, transform coding techniques or statistical coding. Well known compression products are for example Microsoft’s Video for Windows, Apple’s Quick Time, and Intel’s Indeo, though they are not standards de jure.

The Joint Photographic Expert group (JPEG) is a subcomittee responsible for the development of international standards and for digital compression and coding of greyscale and color still images. Because there are a wide range and variety in applications which require a compression scheme, two two generic compression methods have been defined: lossless (non-lossy) and lossy. Both of the classes support various modes of operation to be able to meet the different application requirements.

The MPEG group is another ISO subcomittee and stands for Moving Pictures Expert Group. It is responsible for the development of international standards for digitally coded motion video and its associated audio. So far the group has presented the video standards MPEG 1 and MPEG 2. The intended MPEG 3 standard was skipped, and at the moment they are working on the MPEG 4 standard for compressed video and associated audio for low bit rates [ Garcia, Yeadon and Hutchison, 1996] .

Characters and Character Codes [ McGregor Ross, 1996] are needed to presenting text and symbols. The function of character code (or coded character set) is to allocate a specific pattern of binary digits to each character in a particular set of characters so that the characters may be handled with computers. The purpose of character coding standard is to permit two users, or more correctly their computers, to use and to recognize the same coding for any set of characters.

There are 7 and 8-bit character codes. The ASCII, as we know it is actually a 7-bit ISO 646 character set. Though the 8-bit character code can represent double amount of the data values compared to the 7-bit character set, but has several technical problems within the use of it. Therefore the 8-bit character set has been improved several times , and the UCS (Universal Character Set) has been developed. UCS is ISO 10646-standard, and its American commercial near-equivalent is called Unicode. Members of the Unicode Consortium, such as Microsoft and IBM and other suppliers, are actively bringing implementations of UCS on the market.


2.4 Document Standards

Document standards have been developed for the wide variety of the needs of documents informational content description to the ways of defining the document layout and transferring the documents.

Document can be defined as

"a set of information pertaining to topic, structured for human comprehension, represented by a variety of symbols, stored and handled as a unit" [ Salminen, Kauppinen and Lehtovaara, 1997] .

Another way of describing the document is by its new, rich multimedia and text content, that appears on the two levels of the document. The outer level is the structure of the document as a whole; the inner layer is a collection on information objects which are embedded within that outer containing structure. This kind of documents can be said to be compound documents [ Moore, 1996] .

As an extension of these definitions, a document can be seen as a object which has an intrisinc logical structure because of the informational content of [ Jones, 1991; Maler and El Andaloussi, 1996] and therefore referred as a structured document (such as SGML-document). ODA (Open Document Architecture) han be seen as a set of specifications for a class of document types, a set of embedded types, behavioral receipes and the exact interchange format used by ODA documents [ Moore, 1996] .

A portable document format PDF has been presented by Adobe Systems, Common Ground Software, Farallon Computing and WordPerfect/Novell and other companies. Several newspapers have been published on the WWW as PDF’s. The portable document formats were originally developed for the distribution of independant, navigable and printable electronic documents. The PDF format is used in a family of applicatios called Adobe Acrobat (tm). Because the portable documents need also to be printed within different printers, the PDF has a relationship with Post Script language [ Clarke, 1996] .

The Standard Page Description Language (SPDL) has been accepted as IS 101180 standard. Other Page description formats in addition to PostScript language (de facto standard) are for examplethe Encapsulated PostScript or EPS files. The main purpose of the page description languages is to enable the analogous output of a document even printed with different printer types[ Francis, 1996] .

Here we shortly present the ideas of SGML document standard and compound documents.


2.4.1 SGML and DSSSL document standards

SGML (Standard Generalized Markup Language) is ISO 8879:1986 standard. In SGML, the logical structure of a document information content can be described with the DTD (Document Type Definition) and separated from the document layout structure, that can be defined with the DSSSL (Document Style Semantics and Spesification Language). A SGML document consists of three items: the SGML declaration, the DTD and the text of the document itself. Media objects are to be handled as external object. The DTD defines the tags that are used in the text for identifying the document structure within text. SGML doesn’t restrict the names of the tags to be used (like the HTML language does), the SGML marking is easier to understand than physically-based layout document markup languages [ Bryan and Tucker, 1996] .

Basic logical parts of SGML documents are the element, which is defined in the markup by the start and end tag, and attributes that can be given to elements. Entities can be used for handling shortcuts or references to external files. The possibility to define elements and their relationships to other elements and attributes in the DTD offers a possibility to create complex hierarchical and nonhierarchical structures for describing the logical information structures carried by the documents.

In addition for offering a definition for SGML document layout by the DSSSL Style Language (DSL), the DSSSL also includes the DSSSL Transformation Language (DTL) . Transformation process is used to turn the document into a form that is acceptable to a composition and layout process. In this process the content of the document can be changed, for example the tables of contents can be created and added to the marked places if the styles that the indexes are to be created are being defined in the style spesifications. Withing the DSSSL there is also a language (DSLP) for making querys to the documents[ Hirvonen, 1996] . The DSLP can be used for SGML documents instead, or possibly in the future, in addition of SQL and OQL queries. The DSLP consist more document-related possibilities and features for queries, but in slower than the convetional query languages [ Chelsom, 1996] .


2.4.2 Compound Documents

The first widely accepted component-document framework is Microsoft’s Object Linking and Embedding (OLE). In OLE, a compound document is stored across a number of disk files. A primary document holds the outer container file along with some of the contained elements, the other elements are to be dynamically accessed when needed by the linking routine, which retrieves the wanted object to the document. References of the linked objects are stored in the DocFile (tm) container file. Components and their I/O operations see the stored files as a network of linked objects. The OLE storage architecture is an first generation implementation of component support[ Moore, 1996] .

The basic idea of the OpenDoc is similar. The terminology used with OpenDoc differs from that of OLE, and the uniformity of the storage model is different. OpenDoc’s container is called Bento. The storage form in Bento is more uniform, in that a referenced file is also a Bento container, and therefore the Bento container can contain several levels of objects[ Moore, 1996] .


2.5 Multimedia Standards

HyTime (Hypermedia/Time-based Structuring Language) is an international ISO/IEC 10744 standard developed to support the interchange of hypermedia documents [ Bryan and Tucker, 1996; Tyrväinen, 1997] . HyTime is based on technologies of hypertext linking, music based timing and addressing mechanisms. HyTime is a language for encoding structured hypermedia documents for the purpose of platform independent interchange. Using HyTime the data can be addressed in any time and space co-ordinate set. HyTime defines a standard way of using SGML to describe links and relationships for hypertext, multimedia and hypermedia. HyTime documents are SGML documents that conform to ISO 10744, and they contain HyTime structures encoded in SGML conformant syntax. Architectural forms for creating SGML data structures can be defined with HyTime[ Bryan and Tucker, 1996; Tyrväinen, 1997] .

A HyTime hyperdocument can contain different types of information objects in addition to HyTime documents. A hyperdocument is a collection of one or more hypermedia documents and another information objects that are connected to another directly by hyperlinks or indirectly through a HyTime web. The hub document is the center (or starting) point of this HyTime web[ Bryan and Tucker, 1996; Tyrväinen, 1997] .

The Multimedia Hypermedia Expert Group (MHEG) standard ISO 13522 defines the representation and encoding of multimedia and hypermedia objects in an plattform and application independant way. The MHEG standard supports the fundamendal needs for linking and composition of data structures, and therefore provides a common base for the wide range of multimedia and hypermedia applications to be created in the future. It can also be described as "multimedia/hypermedia postscript". The standard uses MPEG 1, MPEG 2, JPEG and ISO 8859 text. MHEG standard can be seen as a suitable for the applications of CSCW (computer supported multimedia co-operative work), electronic publiching and electronic books, audio-visual telematic systems for training and education and interactive television applications. The basic consepts of MHEG are real-time presentations through the multimedia syncronization functionalities, real-time interchange (with minimal buffering) and minimal resource support in order to integrate low cost terminals in MHEG environments [ Bertrand and König, 1996] .


2.6 Other important Information Standards

The STEP- standard (Standard for the Exchange of Product Model Data) and standards that have been developed under it have been developed to enabling the representation and interchange of product data [ Tucker, 1996] .

The other standards relevant are the standard query languages (SQL and OQL) that have been developed for querying the data stored in widely-used relational and object oriented databases [ Tucker, 1996] . These databases are both suitable for representing documents, allthough they have originally been designed to store single short strings instead of storing the document sections or multimedia document BLOBs [ Koulopoulos and Frappaolo, 1995] . SGML can be viewed as an object-oriented model of documents. The close fit between SGML and object- oriented data model makes ODBMS (Object-oriented or object store DataBase Management Systems) a natural choice for SGML document repository[ Chelsom, 1996] .


3 Distance Learning Material and Electronic Publishing -Using Standards within the Process

Distance Learning material, if contains a large mass of documents, is to be managed like any other large collection of documents. The documentation’s life cycle can be estimated and presented, and used as a tool for estimating the conventional procedures to be done to the material in different market and publishing situations. Usually a publishing process is a part (or covers the whole cycle) of a documentation life cycle, as is therefore a part of the Distance Learning materials life cycle. Virtual learning environment can thus be seen as a virtual publishing environment for electronic publishing. Groupwork is usually typical for this kind of publishing as it is typical for multimedia projects, too.

The main steps and procedures in electonical publishing process can be characterized as:

planning the course content, communication and the education techniques used on the course

planning and documenting the course’s information structure and topics

planning the different data structures needed for storing, querying (if necessary), representing the material within the user interface, and the possible structure and format for user’s paper prints

desicions of the acceptable data formats of the learning material and multimedia objects

gathering the available information, and planning the creation of the rest of the material

gathering the material, possible conversions to storage format

user interface desing and creation


preparing the possible printing formats and structures, conversions if needed

updating and validating the material

There are only two steps on the process that don’t directly benefit from the usage or knowledge about the available standards. It is possible that there are several conversions to be done to the material. If the material is kept in standard format, the conversion process should be easier, not only because most of the applications confront at least one of the most usual standards on their branch. The more than the mass of the material rises, the more of the whole project’s time is to be used for conversions and preparations of the material.

Within a groupwork situation, where different people write or produce different kind of multimedia objects it is important not to agree only of standards, but usually also about the formats, applications and sometimes even application versions to be used for different objects, and the naming issues for different objects and files. If the project is large, or is a "pure" multimedia project, usually a producer and copywriter are both needed to co-ordinate, quide and follow this groupwork.

The issue can be seen throughout a life cycle of a material too. The chain starts when the document or object is created. If it is not in a standard form, the reuse of it can require special applications or several conversions. Sometimes the material is not stored and represented in a same format. This is the case for example if the material is to be presented on a user interface for exampel as HTML , but the pages are being created "on the fly" from the database. Using the database as a store and page creation format enables dynamical seach from the DL material database. Within this kind of environment it is essential to use standard and wide-spread formats, because small change on the applications or non-standard misfunctionality can cause this communication to collapse.


4 Conclusons

There is a wide range of standards and de facto standards available to enable the interchange, conventional storing, querying and representing data structures and formats for information. The OII standards also offers the standards needed for multi- and hypermedia objects and compressing the multimedia data. The standards can cover up every step of the Distance Learning material life cycle, providing consistency, conformity and interoperability between different applications. Therefore, we must not ask why to use standads. Instead, we shoul ask why to risk our information with using non-standard, or not widely accepted data formats for capturing it.




[ Bertrand and König, 1996] Bertrand, F., König, S., MHEG Basics. In:Tucker, H., A., (ed.), The Open Information Interchange Technology Handbook. Technology Apparaisals Ltd, Great Britain, 1996, 187-205.
[ Bryan and Tucker, 1996] Bryan, M., Tucker, H., A., Hypermedia/Time-based Structuring Language (HyTime). In: Tucker, H., A., (ed.), The Open Information Interchange Technology Handbook. Technology Apparaisals Ltd, Great Britain, 1996, 167-185.
[ Chelsom, 1996] Chelsom, J., Document Databases. In: Tucker, H., A., (ed.), The Open Information Interchange Technology Handbook. Technology Apparaisals Ltd, Great Britain, 1996, 209-221.
[ Clarke, 1996] Clarke, M., Portable Documents- an Overview. In: Tucker, H., A., (ed.), The Open Information Interchange Technology Handbook. Technology Apparaisals Ltd, Great Britain, 1996, 153-163.
[ Cover, 1997] Cover, R., The SGML/XML Web Page. 1994-1997 (12.10.1997). [ 12.10.1997]

[ Francis, 1996] Francis, A., Page Description Languages. In: Tucker, H., A., (ed.), The Open Information Interchange Technology Handbook. Technology Apparaisals Ltd, Great Britain, 1996, 141-152.

[ Garcia, Yeadon and Hutchison, 1996]

Gracia, F., J., Yeadon, N., Hutchison, D., Compression Standards: JPEG, H.261 & MPEG. In: Tucker, H., A., (ed.), The Open Information Interchange Technology Handbook. Technology Apparaisals Ltd, Great Britain, 1996, 47-70.
[ Goldfarb, 1990] Goldfarb, C., F.(ed. Rubinsky, Y.), The SGML Handbook. Oxford University Press Inc., New York, 1990.
[ Hirvonen, 1996] Hirvonen, M., Tyylikielet ja niiden soveltaminen lainsäädäntöasiakirjoihin. Tietojärjestelmätieteen pro gradu- tutkielma, Jyväskylän yliopisto, Tietojenkäsittelytieteiden laitos, Jyväskylä, 1996.
[ Holmberg, 1989] Holmberg, B., Theory and Practice of Distance Education. Routledge, London and New York, 1989.
[ Holmberg, 1992] Holmberg, B., Etäopetuksen lähtökohtia. Opetushallitus, VAPK-kustannus, Valtion painatuskeskus, Helsinki, 1992.
[ Jones, 1991] Jones, S., Text and Context. Document Processing and Storage. Springler-Verlag, London, 1991.
[ Karjalainen and Mäkitalo, 1996] Karjalainen, A., Mäkitalo, I., Oppimateriaalin rakennemalli etäopetuksessa. Etäkamu- report "The Structure of the Learning Material in Distance Learning". Project’s internal report.

[ 10.10.1997]

[ Karjalainen, 1997A] Karjalainen, A., Structured Hypercourseware for Distance Learning. Enable 97, 1997, Evitech (Espoo-Vantaa Institute of Technology ) and Learning Inobahn project, 1997. Espoo, May 28.- 30.5.1997.

[ 10.10.1997]

[ Karjalainen, 1997B] Karjalainen, A., Etäoppimateriaalin rakenteistaminen. Pro graduation thesis. Msc Programme of Information Technology, Faculty of Management Information Science, Jyväskylä University, 1997. (to be published on Nov- Dec, 1997)
[ Karjalainen, Komu, Multisilta and Urponen, 1996] Karjalainen, A., Komu, T., Multisilta, J., Urponen, M., Opetusdokumenttien rakenne ja konversiointityökalut, 1996. Etäkamu-report of Research Group of Materials, RG no 2, The Structure of Learning Documents and Conversion Tools, 1996. Project’s internal report.

[ 10.10.1997]

[ Korhonen and Väliharju, 1995] Korhonen, V., Väliharju T., Learning, Learning Environments and Hypermedia. Teoksessa: Theoretical Foundations and Applications of Modern Learning Environments (eds. Pantzar, E., Pohjolainen S., Ruokamo-Saari H., Viteli J.), Tampereen yliopiston tietokonekeskuksen julkaisuja n:o 1, Tietokonekeskus/Hyperemedialaboratorio, Tampere University, Tampere, Finland, 1995, 49-69.
[ Koulopoulos and Frappaolo, 1995] Koulopoulos, T., M., Frappaolo, C., Electronic Document Management Systems. A Portable Consultant. McGraw-Hill, Inc., U.S.A., 1995.
[ Lehto, 1997A] Lehto, T., Kyrilliikkaohjeita, Etäkamu-project’s internal report, 1997. [ 10.10.1997]

[ Lehto, 1997B] Toolbook Webbiin! Etäkamu-project’s internal report of Asymetrix Toolbook and Neuron-plugin usage, 1997. [ 1.10.1997]

[ MacMorrow, 1993] MacMorrow, N., Cracking the code: multimedia standards and what they mean. Online Information 93, Proceedings of the17th International Online Information Meeting.7-9 Dec., 1993, London, England. Learned Information, Oxford and New Jersey, 1993. 235-241.
[ Maler and El Andaloussi, 1996] Maler, E., El Andaloussi, J., Developing SGML DTDs. From text to model to markup. Prentice Hall, New Jersey, 1996.
[ McGregor Ross, 1996] McGregor Ross, H., Characters and Character Codes. In: Tucker, H., A., (ed.), The Open Information Interchange Technology Handbook. Technology Apparaisals Ltd, Great Britain, 1996, 27-46.
[ Moore, 1996] Moore, R., Document Architectures and Container Formats- an Overview. In: Tucker, H., A., (ed.), The Open Information Interchange Technology Handbook. Technology Apparaisals Ltd, Great Britain, 1996, 75-85.
[ Mumford, 1996] Mumford, A., Graphics Interchange Formats.In:Tucker, H., A., (ed.), The Open Information Interchange Technology Handbook. Technology Apparaisals Ltd, Great Britain, 1996, 3-26.
[ Nykänen and Ala-Rantala, 1997] Nykänen, O., Ala-Rantala, M., A Design for Hypermedia-Based Learning Environment. Human Computer Interaction and Educational Tools, 1997, IFIP WG 3.3 Working Conference. Sozopol, Bulgaria, May 27th - 28th 1997. alaranta/hble.html [ 10.10.1997]

[ Ruokamo-Saari, 1995] Ruokamo-Saari, H., Mathematical Giftedness and Development of Solving Mathematical Word Problems in Hypermedia Learning Environment. In: Pantzar, E., Pohjolainen S., Ruokamo-Saari H., Viteli J., (eds.), Theoretical Foundations and Applications of Modern Learning Environments, Tampereen tietokonekeskuksen julkaisuja n:o 1, Tietokonekeskus/Hyperemedialaboratorio, Tampere University, Tampere, Finland, 1995, 103-125.

[ Salminen, Kauppinen and Lehtovaara, 1997] Salminen, A., Kauppinen, K., Lehtovaara, M., Towards a Methodology for Document Analysis. Journal of the American Society for Information Science, 48 (7):644-655. Special Issue on Structured Information/ Standards for Document Architecture. John Wiley & Sons Inc., 1997.

[ Travis and Waldt, 1995] Travis, B., Waldt, D., The SGML Implementation Guide, A Blueprint for SGML Migration. Springer-Verlag, Berlin, Heidelberg, 1995.
[ Tucker, 1996] Tucker, H., A., (ed.), The Open Information Interchange Technology Handbook. Technology Apparaisals Ltd, Great Britain, 1996.
[ Tyrväinen, 1997] Tyrväinen, P., HyTime. [ 09.06.1997] .
[ W3 Org., 1996] [ 08.01.1996]