Because we have been dealing directly with the authors of Ochre, we have been able to have extensions added to the programming language itself which greatly assisted the development of the VI user interface. These and other enhancements are now an integral part of the commercial Ochre product. To our knowledge, this is the only 4GL designed with the needs of VI users in mind. Some of these principles were set out before development of the user interface, others were recognised as we moved further into the development process. We decided to develop two user interfaces, optimised for sighted and blind users respectively.
Any user can choose either the VI or the regular interface before starting the application.
Our experimentation demonstrated that developing a single user interface to meet the needs of both groups of users would have compromised efficiency, accuracy and confidence for both groups. We considered this aspect of design to be essential to ensure effective training, documentation and support, and to ensure meaningful communication between users of the system. This commonality allows sighted users to be able to understand VI screens when working with a BVI colleague on an issue. It sometimes took quite a bit of experimentation to develop a way of making some information meaningfully available to BVI users, but it was considered essential to ensure this. Punctuation characters are extensively employed to provide screen layout, colour and context information to users of the VI interface.