1. A description of the functionality which has been implemented and how to access that functionality through the user interface.
2. It should be made clear which parts of the system are not implemented. Manual writers should not leave users to find this out when problems arise.
3. A description of how to recover from difficulties. Users are working with an experimental system and it is inevitable that things will go wrong. Information about how they can get back to a known system state and restart use of the system should be included.
4. If users have to install the prototype themselves, installation instructions should be provided.