Development of the VRML 97 International Standard

George S. Carson, Richard F. Puk and Rikk Carey

(c) Copyright George S. Carson, and Richard F. Puk and Rikk Carey 1997, 1998. Permission to copy and distribute this document is hereby granted provided that this notice is retained on all copies and that the document is copied and/or distributed in its entirety without alteration. This work has been accepted for publication. Copyright may be transferred without further notice and the accepted version may then be posted by the publisher.

Abstract

International Standards for Information Technology are increasingly being developed by standards committees in partnership with industry consortia. A good illustration of this is VRML [1]. The early stages of development were carried out within the VRML community and were characterized by an open Request for Proposals, debate over the relative merits of the submissions using an Internet e-mail discussion list, and selection of a winner. The final stages of development were carried out as a cooperative effort between the International Standards and VRML communities. This development methodology is widely applicable to development of future information technology standards.

Table of contents

1 History of VRML Standardization
  1.1 The Early Days
  1.2 E-mail discussion lists
  1.3 Early work in ISO
  1.4 The VRML Architecture Group (VAG)
  1.5 ISO and IEC Get Involved
  1.6 Formal Cooperation Begins
  1.7 The Committee Draft Stage
  1.8 The Draft International Standard Stage
  1.9 The VRML Consortium
  1.10 The Present

2 The VRML Community

3 Lessons Learned

4 The Future

5 Conclusion
  5.1 Acknowledgments
  5.2 The Authors

References

1 History of VRML Standardization

1.1 The Early Days

Several independent projects provided the foundations for VRML. In 1994, Pesce and Parisi developed Labyrinth, an early prototype 3D user interface for the Internet, and presented their work at the first World Wide Web Conference in Geneva VRML [2]. In 1989, Carey and Strauss started the Open Inventor project at Silicon Graphics to build a 3D computer graphics environment that enabled a broad, multi-platform application framework and expanded 3D graphics into mainstream markets VRML [3]. Open Inventor included a file format designed as an interchange format for 3D applications. Eventually, the Labyrinth and Inventor teams would collaborate to form the basis for VRML. Besides Open Inventor and Labyrinth, other major projects that influenced VRML were:

Soon after the 1994 WWW conference, the www-vrml e-mail discussion list was formed. The list was devoted to the creation of a 3D interface for the Internet. After much discussion, the group developed a series of requirements and issued an open Request for Proposals. Five submissions were received:

After lively discussions, list participants voted by sending e-mail to the list moderators. The entire process was ad hoc and informal, but was fast and simple to execute. The Open Inventor-based proposal received the largest number of the few hundred votes by a small margin, OOGL came in second and the other three proposals each received far fewer votes. Thus, the Open Inventor proposal became the working document for the first VRML specification. Bell and others refined the proposal into a first draft that was presented at the second International World Wide Web Conference in October 1994.

The early appearance of VRML products and an early VRML buy-in by major corporations were essential economic factors supporting the standardization effort. In April of 1995, Silicon Graphics released WebSpace Navigator, the first VRML browser. Silicon Graphics licensed WebSpace to Template Graphics to be ported to variety of platforms, including Windows. Intervista's WorldView 1.0 and Paper's WebFX were two other influential early browsers. Microsoft licensed WorldView 1.0 from Intervista and bundled it into Internet Explorer 2.0 in June of 1995. In February of 1996, Netscape bought Paper, Inc., integrated WebFX (later to be called Live3D) and endorsed the Silicon Graphics effort.

1.2 E-mail discussion lists

Since moderated e-mail discussions were important to the evolution of VRML, it is worthwhile to examine how these discussions worked in more detail. The key elements were:

1.3 Early work in ISO

In parallel with the evolution of VRML in the web community, there were several attempts to initiate a 3D graphical metafile project within the Computer Graphics and Imaging Processing Subcommittee (SC 24) of Joint Technical Committee 1 (JTC 1) of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC)

Prior to 1994 there was interest within the standards community, but there was insufficient industry support to initiate a project. In 1994, SC 24 issued a call for submissions of candidate formats. Apple Computer, Silicon Graphics and others made presentations at a meeting in Airlie, Virginia, USA in October 1994. SC 24 carefully reviewed each submission against a list of requirements and determined that the Silicon Graphics submission based on the Open Inventor format was best. SC 24 also decided that there was sufficient industry support for a New Work Item Proposal to be prepared and submitted for approval. At this point, although both SC 24 and the VRML community had selected the Open Inventor format as the base specification, the work in each arena was still proceeding independently.

1.4 The VRML Architecture Group (VAG)

During the summer of 1995, it became evident to the ad hoc organizers of VRML that more order was needed to better manage the evolution of the specification because:

The best way to provide the needed structure was debated by the organizers. Some felt that it was time to form a "VRML Consortium." Several large, influential corporations that wanted to participate in the evolution of VRML supported this view. Others were opposed because they felt that the VRML community still needed to move rapidly, and that a consortium of competing companies would slow the process down. The perception that rapid progress was required was fueled by the realization that VRML 1.0 was inadequate and that a next generation specification must be developed very quickly. The organizers eventually agreed to form a small, technical body to govern the near-term future of VRML, with plans to create an industry consortium once the specification was stable enough.

Thus, the VRML Architecture Group (VAG) was formed. The goal of this self-selected group was to continue the technical evolution of the specification according to the consensus-based requirements of the VRML community. Besides Bell, Carey, Parisi and Pesce, six others were invited to balance representation and provide expertise in other technical areas (e.g., networking, content creation, and multimedia). The other initial members were Brian Blau, Jan Hardenbergh, Jon Marbry, Tom Meyer, Mitra, and William Martens. The plan was to start from VRML 1.0, allow the VAG to design the next generation specification, and review the resulting proposal on the www-vrml e-mail list. There was no plan to issue a Request For Proposals (RFP) for a new specification.

1.5 ISO and IEC Get Involved

By late 1995 all major vendors supporting were supporting the VRML specification. Members of the VAG approached several organizations including W3C, IETF and ISO to explore the possibility of making VRML into a formal standard. Of these only ISO was interested. SC 24 realized that a separate ISO effort to develop a 3D metafile format was no longer justified. Thus the first discussions on merging the VRML and the SC 24 3D metafile work took place in late 1995. Members of the VAG also realized that the long experience of SC 24 in standards development could be beneficial.

As cooperation between the VAG and SC 24 was beginning, there was a raging debate about the future of VRML on the www-vrml email list. Many contributors wanted a dramatic revision of the specification - one that included "behaviors" (a term that meant different things to different people). In December 1995, both Silicon Graphics and Microsoft announced proposals for the future of the VRML standard. Silicon Graphics' was called Moving Worlds and was based on a collaborative effort with Mitra and Sony Research. It was a significant advance over VRML 1.0, in terms of behaviors, interaction, and animation, but retained the VRML 1.0 (i.e., Inventor) philosophy and style. Microsoft's ActiveVRML was a dramatic departure from VRML 1.0. It was based on the ML programming language and provided a declarative programming language solution to the problem.

During this period, the VAG moderated discussions on the list and guided the process. In the pre-VAG days as VRML 1.0 was finalized, this process had consisted of releasing various revisions of the specification and managing the comment resolution process. It VAG quickly realized that they could not create the VRML 2.0 specification on their own, so the group shifted gears and issued an RFP. From December 1995 on, they stopped acting as a technical committee and started acting as a process committee.

In retrospect, the VRML community was able to move fast in adopting VRML 1.0 because the Open Inventor experience provided a designed, battle-tested, and mature specification. Thus, it was a comparatively simple design task to update and revise VRML 1.0. When the VAG tried a more formidable design task (VRML 2.0), problems arose and eventually caused the approach to fail. Once the VAG became a process committee, things improved. The task of managing the work was much simpler than doing it.

In mid-December 1995, the VAG issued design criteria and a RFP for VRML 2.0. The RFP was issued on January 4, 1996 with a deadline of February 2. They asked for complete proposals and provided technical guidelines representing the requirements. Six proposals were received: Active VRML from Microsoft, Dynamic Worlds from GMD and others, HoloWeb from Sun, Moving Worlds from Silicon Graphics and others, Out of this World from Apple, and Reactive Virtual Environment from IBM Japan.

A VAG meeting took place on February 5-6, 1996 in San Francisco to draft the process for selecting the winning submission that would become VRML 2.0. At this meeting, representatives from SC 24 formally met with the full VAG for the first time. It was mutually agreed to pursue ISO standardization of the VRML 2.0 Specification that would emerge from the selection process. Immediately after the meeting, the VAG issued a statement that described a 6-week public review and voting process. Anyone was free to visit a VAG-hosted Web page, vote on each of the proposals ("Strongly in favor" to "Strongly against") individually, and pick their favorite. To encourage discussion and debate, voting results were available even during the vote, and each person could change their vote at any time during the voting period. The only restriction on voting was a stern admonition to read the proposals and vote based on the proposals' technical merits. Ballot-box stuffing was discouraged by requiring a valid email address (a vote confirmation message was sent to the email address given, and if the email was not deliverable then the vote was discarded), and by stating that the list of email addresses of all voters would be made public. This voting process worked surprisingly well. Just under 200 votes were received, reflecting the number of people who properly evaluated the proposals.

The final results showed Moving Worlds a strong favorite, and VAG members unanimously agreed to recommend it as the working draft for VRML 2.0 VRML [4]. At this point, ISO work began as the Moving Worlds specification was circulated within the SC 24 Metafiles Rapporteur Group as a Working Draft.

1.6 Formal Cooperation Begins

In June 1996, a representative of the VAG attended the SC 24 meeting in Kyoto, Japan VRML [5]. At that meeting, the final details of a Cooperative Agreement governing work on VRML 2.0 were decided VRML [6]. The purpose of this agreement was to how a public specification (i.e., one whose text is available for use with few or no restrictions) such as VRML was to be transposed into an International Standard. Both parties wanted to achieve several key goals with this agreement:

With the Cooperative Agreement negotiated and approved, joint work began on the VRML International Standard. Based on comments received on the Working Draft, VAG and SC 24 representatives agreed on necessary changes to create a document of sufficient quality to serve as a Committee Draft. Two co-editors were appointed, one from SC 24 (Richard Puk) and one from the VAG (Rikk Carey) and work began to cooperatively produce the single document that would serve as the VAG's VRML 2.0 Specification and as SC 24's CD 14772-1.

1.7 The Committee Draft Stage

It is useful to examine how the Moving Worlds Specification was converted into CD 14772-1, VRML 2.0 [8]. The changes are typical of those needed to industry specifications since they are often "after the fact" descriptions of an implementation rather than specifications purposely written to permit multiple, independent, interoperable implementations. The major changes were:

It took the coeditors and others who assisted them almost two months to make all required changes. On August 4, 1996, the resulting final version of the VRML 2.0 specification was released by the VAG at SIGGRAPH 96 in New Orleans, Louisiana and the CD ballot was started within ISO [10]. Even at this early stage, recognizable improvements in quality and clarity were evident.

1.8 The Draft International Standard Stage

The CD ballot for VRML closed in December 1996. During the ballot period, VAG members Rikk Carey and Gavin Bell as well as Chris Marrin, an author of the Moving Worlds proposal, monitored the simultaneous review of VRML 2.0 that was taking place on the www-vrml list. They documented any issues raised and resolved on the list that suggested changes should be made in the specification. The consolidated comments from the list, plus some others from VAG members as individuals, were submitted as comments on the CD ballot.

This CD ballot resulted in over 200 pages of detailed technical and editorial comments. Of the hundred or so comments from the VAG, most were minor technical comments. The overwhelming majority of comments were from SC 24 National Bodies (i.e., countries). These comments were mostly editorial in nature and many concerned places where the specification was imprecise or ambiguous and clarification was desired. All comments were resolved at a joint SC 24 and VAG editing meeting December 7-9, 1996.

It is instructive to look at the nature of the comments and the resulting changes in the document. The major editorial changes in the DIS version from the CD version were:

There were only a few significant technical changes required as the VRML CD text was turned into the DIS text by the ISO editors and the dozen or so experts who assisted them. These changes were:

After all editorial and technical comments were resolved, a detailed response document was prepared describing each change to the CD text [8]. This was standard ISO procedure and differs from how comments were handled "on the fly" during discussions on the www-vrml list.

The simultaneous and coordinated reviews in both the VRML community and SC 24 each had its benefits. List discussions allowed a rapid paced exchange of ideas, but tended to be focused on mostly "shallow" technical aspects as uncovered contemporaneously by implementers and users. The SC 24 review took a deeper and broader look at the specification as a whole with an eye towards making it more usable by those beyond the initial implementers. The two types of review were complementary, and each resulted in improvements that will have lasting benefits.

Due to the volume of comments, it took the editors two months to prepare an "editor's draft". Individuals who had attended the editing meeting further reviewed this draft to insure that all responses had been correctly applied. This process took several additional months. Following this, text for the Draft International Standard (DIS) was prepared and posted on the World Wide Web on April 6, 1997.

1.9 The VRML Consortium

By the middle of 1996 it was evident that key vendors who wanted to make a commitment to VRML technology were uneasy about entrusting the future to either an informal group such as the VAG or solely to an ISO standards committee. Since the VAG members had been hand picked by only a few of the original organizers, there were concerns about how representative they were of the broad VRML community. Both the lack of a formal leader and the lack of well-defined and documented processes led to the VAG having a perceived lack of credibility. These organizations would rather work with a formal standards body or even another corporation where the outcome would be more predictable. It was suggested that Silicon Graphics should form its own VRML ARB (Architecture Review Board, much like the OpenGL ARB) in the hopes of establishing a formal body that they could join and work with.

In response to these concerns, a meeting was held during SIGGRAPH in August 1996 about establishing a consortium to promote VRML. As a result, a Consortium Working Group (CWG) comprised of representatives from industry and academia was chartered with establishing the VRML Consortium. An e-mail discussion list was established and the CWG issued a RFP for creating the consortium, including determining its organization and bylaws. The CWG received and reviewed three proposals. It recommended a plan presented by Deepak Kamlani of Interprise Ventures and Grayson Schlichting of the Broad Alliance for Multimedia Technology and Applications (BAMTA) for establishing the administrative infrastructure for the consortium. Following this selection, the proposal was discussed on the e-mail discussion group where it received positive feedback. At this point, planning progressed to satisfying the legal prerequisites for incorporating the Consortium.

In October 1996, members of the VAG assisted the CWG in refining the proposed VRML Consortium by-laws, based on a first draft provided by Interprise Ventures and based on the by-laws of two successful high-tech consortia. The second draft was discussed in November 1996 and further modified. The CWG and VAG approved the by-laws on November 15, 1996 and formed an interim Board of Directors of 15 members, appointed interim officers, and agreed to incorporate the VRML Consortium as a legal entity. The VRML Consortium, Inc. was established as a nonprofit corporation with the mission of fostering and evangelizing VRML as the open standard for 3D multimedia and shared virtual worlds on the Internet.

In January 1997, once the VRML Consortium was established and sufficient number of organizations had joined as voting members, elections for a new Board of Directors were held in accordance with the approved by-laws. Control was passed from the interim to the elected Board of Directors at the VRML 97 Symposium in Monterey, California on February 23, 1997. Initial members of the Consortium included thirty five leading Internet companies: 3Dlabs, Inc., Apple Computer, Inc., Axial Systems, Inc., Black Sun Interactive, Inc., Construct Internet Design Co., dFORM Inc., Division Ltd., First Virtual Holdings, Inc., IBM Corp., Integrated Data Systems, Intel Corp., Intervista Software, Inc., Kinetix, Microsoft Corp., Mitsubishi Electric Research Labs, Inc., Netscape Communications Corp., Oracle Corp., ParaGraph International, S3, Inc., SENSE8 Corp., Silicon Graphics, Inc., Sony Corp., Superscape Inc., Template Graphics Software, Inc. and Visible Decisions Inc. Other members included academic institutions (such as the Naval Postgraduate School, Brown University and the San Diego Supercomputer Center) and governmental entities (such as the USA's National Institute of Standards and Technology (NIST)). During the first Board of Directors meeting, the VRML Consortium accepted and endorsed the existing Cooperative Agreement with JTC 1.

Since the founding of the VRML Consortium, considerable interest has been shown in VRML 97 and its success has broadened the scope of interest in 3D on the World Wide Web. To more adequately represent this more varied interest, in September 1998, the VRML Consortium voted to become the Web 3D Consortium with a widened mandate to represent all 3D technology for the Web. The VRML Consortium is in the process of formally changing its name and updating its by-laws.

1.10 The Present

Recall that the CD ballot for VRML closed in December 1996 and the coeditors worked for four months, producing the text of DIS 14772-1 in April 1997. This was then balloted within ISO/IEC JTC 1. The comments from the DIS ballot were processed in October 1997 [11]. There were many fewer comments during this review attesting to an improvement in quality of the specification. Making the required changes took a further two months. In December 1997, the final text was submitted for publication as VRML 97 [1].

To facilitate printing the standard, separate hardcopy versions for ISO (with ISO copyrights) and the VRML Consortium (with VRML Consortium copyrights) were produced in Word 97. Page numbers were added for easier reference. The ISO hardcopy version has been printed and is accompanied by a CD-ROM containing the HTML version. The VRML Consortium hardcopy and softcopy versions are available from http://www.vrml.org/Specifications.

2 The VRML Community

The VRML community has diverse participation. While there is representation from the research community, there is also wide participation from both the Internet development community as well as from the creative community who design VRML content for the web. Several key factors had an important influence on the development of VRML:

Because of the above factors, the VRML community was able to coalesce and work together. While a few of the participants had worked together before, most became acquainted during the development effort, so it was not a case of a team that had worked together successfully before being applied to a new problem.

3 Lessons Learned

The development of the VRML standard is one of very few successful examples of an "Internet" standard being processed to become an International Standard. Initially, considerable effort was expended by the leadership of both the VRML community and of SC 24 to overcome the traditional hostility and clash of styles between the Internet community and ISO. Today, each community has come to realize the value that the other contributes to the standardization process and how a coordinated approach based on combining the best that each community has to offer can be an effective model for standards development. The three most important lessons learned were:

In the early and intensely creative stages of specification development, the use of Internet style discussion lists was very valuable. The VRML Community used this technique to great success in soliciting proposals, evaluating them, and refining their initial products. Individuals from all major interested vendors participated, and this helped build worldwide consensus. VRML was developed as an open standard instilled with the principle that high quality infrastructures can be built in the open on level playing fields. The result has been faster and better products as well as more interesting and productive market competition based on value, not history or platform dependence.

The product of an Internet style development is often referred to as "rough consensus and working code." When the experts of SC 24 got involved, it was evident that this was a fair characterization of the VRML 2.0 Specification. The VRML Community had created an excellent specification based on the right ideas, but one that still needed editorial and technical work to attain the quality expected of an International Standard.

Since the initial VRML 2.0 draft was based on new technology, the experts of SC 24 worked hard to increase the descriptiveness of the early drafts. The first result was CD quality text was produced in about 2 months. The step to DIS required considerably more effort and clearly showed the value of SC 24 processes. When a standard moves to DIS, it is difficult, if not impossible, to accomplish the necessary work by an Internet-style discussion list. What is required is careful, thoughtful review by independent groups of experts whose comments are consolidated and resolved at an editing meeting. In the case of VRML, it took a three day meeting by about a dozen experts to process the 200 pages of comments, followed by four additional months of work by the co-editors to make the agreed changes. A less intensive similar meeting was needed nine months later to process the comments on the DIS text and produce the final standard.

VRML was developed under a cooperative agreement that proved key to keeping the work on track and resolving problems. Among the most important elements of the agreement was the constraint that no unnecessary technical changes would be made. Although at least four significant technical changes were actually made, both parties recognized each as being necessary. A second key constraint was that the work be accomplished on the shortest feasible schedule.

In June 1997, SC 24 and the VRML Consortium mutually adopted the first revision to the original Cooperative Agreement. Under the revised agreement, SC 24 and the VRML Consortium will continue their cooperation to develop specifications for other areas of VRML technology and to make these into International Standards where appropriate. Early technical work will be accomplished principally within the Consortium's Working Groups where SC 24 experts as well any other individuals are free to participate without necessarily being Consortium members. Later stage technical and editorial work will be accomplished within SC 24 (with liaison from the VRML Consortium).

4 The Future

Early in the development of VRML, it was decided that ambitious features (such as multi-user interaction or autonomous creatures that can sense and react to their environment) would not be part of the initial version. VRML Consortium Working Groups (with participation of SC 24 experts) are currently specifying, implementing and testing extensions in many areas. (A list of all approved working groups can be found at: http://www.vrml.org/WorkingGroups/ ). The best and most widely accepted extensions will become VRML Consortium Standards and then be processed to become International Standards. Among the areas of active current work are:

In addition, work has begun to identify requirements for a next generation VRML. The goal is to overcome some limitations in VRML 97 while maintaining as much compatibility as feasible given the constraints inherent in new requirements. When a draft is available, next generation VRML will be processed to become an International Standard, but this work will proceed only after sufficient agreement on requirements. Meanwhile, a first amendment to VRML 97 is being considered. This amendment will change VRML 97 to enhance its ability of interact with other technologies including MPEG-4.

Both SC 24 and the VRML Consortium intend to follow consortium procedures for designing the functionality of new specifications and to decide whether a specification is appropriate for standardization. The product of consortium work can be either be a report not intended for standardization or a specification for additional functionality that may be submitted for standardization. The VRML Consortium has created the VRML Review Board (VRB) to oversee these activities and to determine the viability of each specification. SC 24 has a liaison representative who participates in the work of the VRB and serves as the primary technical interface between the two organizations. At a management level, the Chairman of SC 24 and the President of the VRML Consortium coordinate directly on all issues of mutual concern.

5 Conclusion

The processing of VRML marked many firsts for the development of International Standards, including the completion of a project from start to finish in record time (less than 18 months) and the first International Standard published in HTML. The cooperative work of SC 24 and the VRML Consortium shows how an industry specification can be processed into an International Standard through a normal standards development process without either unnecessary delay or needless technical change. It also illustrates the substantial value that the technical experts experienced in the development of International Standards can add to a specification. In terms of increased clarity and precision, this value will have lasting benefits.

5.1 Acknowledgments

Mark Pesce and Tony Parisi started the activities that led to the creation of VRML. The other members of the VAG who guided the development work during the critical period, were Gavin Bell, Brian Blau, Rikk Carey, Jan Hardenbergh, Jon Marbry, William Martens, Tom Meyer, and Mitra. Chris Marrin and Gavin Bell were co-authors with Rikk Carey of the VRML 2.0 Specification. Koichi Matsuda (Sony) was a key contributor to the Java annex, Jan Hardenberg was a key contributor to the JavaScript annex, and many other individuals from the www-vrml list also made contributions. Silicon Graphics donated the Open Inventor file format and tools to the VRML community and contributed significant engineering efforts. Finally, the work of the VRML Consortium and its President, Neil Trevett, in making VRML a reality in the marketplace must be recognized.

Within the ISO and IEC community, many people contributed to the success of VRML. Authors George S. Carson and Richard Puk were assisted within SC 24 by Lofton Henderson, Metafiles Rapporteur, and the many experts of his group. The staff of the Information Technology Task Force at ISO Central Secretariat, notably Keith Brannon, fostered the cooperative atmosphere that allowed VRML to be advanced quickly while still following ISO and JTC 1 procedures.

5.2 The Authors

George S. Carson (carson@siggraph.org) is President of GSC Associates Inc. of Las Cruces, New Mexico. He is the Chairman of ISO/IEC JTC 1/SC 24, Computer Graphics and Image Processing.

Richard F. Puk (puk@igraphics.com) is President of Intelligraphics Incorporated of Carlsbad, California. He is co-editor of ISO/IEC DIS 14772-1, VRML.

Rikk Carey (rikk@wasabisoft.com) is President of Wasabi Software of Los Altos, California. He is co-editor of ISO/IEC 14772-1, VRML 97, and co-author of "The VRML 97 Reference Manual" at http://www.best.com/~rikk/Book.

References

  1. VRML Consortium, the International Organization for Standardization and the International Electrotechnical Commission, The Virtual Reality Modeling Language, ISO/IEC IS 14772-1, December 1997, http://www.vrml.org/Specifications
  2. J. Wernecke, The Inventor Mentor: Programming Object-Oriented 3D Graphics with Open Inventor, Release 2, Addison-Wesley, Reading Massachusetts, 1994.
  3. M. Pesce, P. Kennard, and A. Parisi, Cyberspace, http://www.hyperreal.org/~mpesce/www.html, May 1994.
  4. J. Hartman and J. Wernecke, The VRML 2.0 Handbook, Addison-Wesley, Reading Massachusetts, 1996.
  5. ISO/IEC JTC 1/SC 24/N1575, "CGM Rapporteur Group Meeting, Kyoto Japan, 14-18 June 1996", June 1996.
  6. ISO/IEC JTC 1/SC 24/N1630: "Co-operative working agreement between SC 24 and VRML Architecture Group", 5 August 1996 (revised as N 1773 on 13 August 1997)
  7. ISO and IEC, Procedures for the Technical Work of ISO/IEC JTC 1 on Information Technology, Geneva Switzerland, (Third Edition, 1995) (http://www.iso.ch/dire/jtc1/directives.html).
  8. ISO/IEC JTC 1/SC 24/N1666, "Disposition of comments report on ISO/IEC CD 14772 : Virtual Reality Modeling Language (VRML) (SC 24 N 1596)", 24 April 1997.
  9. ISO and IEC, ISO/IEC Directives, Part 3, Rules for the structure and drafting of International Standards, (Third edition, 1997) (ftp://ftp.iec.ch/pub/.contents.html).
  10. VRML Architecture Group, the International Organization for Standardization and the International Electrotechnical Commission, The Virtual Reality Modeling Language Specification, Version 2.0, ISO/IEC CD 14772-1, 4 August 1996.
  11. ISO/IEC JTC 1/SC 24/N1797, "Summary of voting and comments received on ISO/IEC DIS 14772-1: Virtual Reality Modeling Language", 12 November 1997.
  12. R. Carey and Gavin Bell, The Annotated VRML 97 Reference Manual, Addison-Wesley, Reading Massachusetts, 1997, (http://www.best.com/~rikk/Book).