1.1. how much (in percent) of the functionality of the HFA do you know?
In MS-Word I probably know about 50% of the functionality.

1.2. how do you learn new functionality?
I learn new functionality by using the passive help system or by guesswork. By guesswork I mean looking around in the menus and trying to find what I'm looking for.

1.3. for MS-Word users: is there a command in MS-Word which "transposes two characters" (e.g., "leanr" becomes "learn" by positioning the cursor between n and r and executing the command)? I checked and could not find one, but many times spelling will be automatically corrected for you.

2. what have YOU learnt "on demand" in YOUR life? Briefly describe the most prominent examples.
I learned Jakarta Tomcat and other web service technologies for research projects and for work. I worked with Roger King and a group of students last summer to develop a PDA application for medical professionals to enter data on children with disabilities. The problem was that medical professionals had to enter data on paper which included answers to hundreds of questions about the capabilities to the child. It was not really possible to sit in front of a computer and answer the questions because it involved a lot of observation. After the data was recorded on paper it had to be re-entered into a database system. We provided a way for the data to be entered into a PDA and then uploaded automatically into a DB system. I also learned Java Swing for a final project I did last semester that required a user interface. For Game Programming with Clayton Lewis and Alex Repenning this semester I have had to learn a commercial game engine that my group and I purchased together. This has been very slow-going, but rewarding. Those are the major ones.

3. what do people have to know to be able to learn on demand?
This highly depends. I would not have been able to learn any of the above things I mentioned without extensive programming experience. People have to know something with which to relate the current context. Some kind of foundation is necessary when trying to build new knowledge.

4. why should one "learn on demand" instead of relying on "use on demand"?
Learning on demand adds new knowledge to current knowledge whereas use on demand does not. It seems to me that some learning must occur before something can be used properly. One should always be trying to learn something new instead of just tinkering until a goal is achieved. It is important to grasp why the goal was achieved, what steps were involved so that it can be done more efficiently next time. When trying to do something complex in MS-Word it is usually more productive to use the passive help system and more will be learned this way. By looking through the help system, one might find the answer to other questions inadvertently as well as the current one which makes it a good learning experience.

5. which computer systems have you encountered which

5.1. have a User Modeling Component?
MS-Office applications.
Microsoft Windows XP OS
These systems are highly configurable which makes them adaptable to a user's preferences.
Eclipse IDE and Visual Studio fit here too because they are highly cofigurable with hundreds of plugins and options.
I just have to ask the question, how well can I make this HFA work for me personally?

5.2. supported learning on demand?
MS-Office applications.
Visual Studio .NET
Eclipse IDE
Microsoft Windows XP OS
Adobe Applications
Macromedia Applications
I think that any application that has good documentation and a good passive help system support learning on demand.