1. Note that in this simple example illustrating the DNLF we do not intend to imply a rigid "stored-schema model" of fixed symbolic representations that exist in a person's brain. Instead, from a situated action perspective, the neural structures and processes coordinating perception and action arise during activity itself (Clancey, 1993; Edelman, 1992; Greeno & Moore, 1993). Indeed, the DNLF is partly intended to help identify ways that network learning environments may be understood and utilized from a situated action perspective.

2. The use of multiple, coordinated metaphors for network learning environments is important as it has been found that a single analogy can misrepresent important facets of a complex topic (Feltovich, Spiro, & Coulson, 1989; Spiro, Feltovich, Coulson, & Anderson, 1989).

3. Recent research has begun to identify ways in which basic epistemic beliefs about the nature of learning can influence learning in hypertext learning environments (Jacobson, Maouri, Mishra, & Kolar, in press; Jacobson & Spiro, 1995).

4. It is interesting to note that much of the most innovative network software development is using a hyperlinked orientation either implicitly (e.g., TurboGopher's Bookmarks which are simple hyperlinks to Gopher nodes) or explicitly (e.g., World Wide Web which creates very elaborate documents with hyperlinks to distributed network text and multimedia nodes.

5. However, merely linking text and multimedia nodes together on an electronic network is unlikely to result in substantive learning of complex knowledge (Jacobson, 1994).

6. We illustrate different functions of Message Assistant using selected messages from a network-based learning activity, the Zero Gravity Design Project, that was conducted during the 1991-92 school year. (All personal identification information from non-research participants have been removed.) Students from a number of schools around the country considered what life in a zero gravity environment such as a space station would be like. Next, teams of students focused on designing a specific aspect of zero gravity life that students might experience, such as eating and food, recreation, or school and education. They sent messages over the Internet and FrEdMail networks to other students, teachers, university faculty, researchers, and scientists to ask questions, share ideas, and discuss their designs. As the Message Assistant was under development at that time, the students did not use the program. However, this project generated over 400 messages and thus illustrates the logistical and cognitive difficulty students and students might experience as they try to manage and learn from the significant information generated by a large scale distributed network learning project.

7. Many network based projects, such as Zero-g World Design, are implemented with an "e-mail reflector" that is simply a list of all the electronic mail addresses of the participants. Participants send messages to a single electronic address and the reflector automatically re-sends the messages to all of the people on the list. So a possible scenario is that multiple participants in a network learning project would want to hyperlink the same project message set sent by the e-mail reflector according to their own personal information needs and conceptual frameworks.

8. For a further discussion of fixed and variable hyperlinks, see Jacobson et al. (in press).

9. A teacher could use the Knowledge Spaces metaphor with her students as part of general discussions and activities involving network learning environments, and the term "views" in the Message Assistant program would simply be a subtle reaffirmation of the general conceptual model.