We should not have to fundamentally change the way we work to suit the tool. There should be a close match between the notations supported by the tool and that of the textbooks. Supports the methodology of our choice - 3 Customisation Tools which can be customised are advantageous because our requirements may change. Access to the model is important so that we can do things not envisaged by the tool builders. The tool should be language independent.
Models allow a discussion of the software at a higher level of abstraction than the code.
Models can be drawn best and most easily discussed among collaborating people through the use of tools. We want the tool to be able to cope with more than one developer working on the model from different sites. This might be done with a single repository or with a distrubuted repository and with or without duplication of information at different sites. This implies that the model must be represented by many small ascii files. The user interface should be easy to understand.