The Viewpoint concept has broadened to some extent. Some advocate technical models - from procedural through to object oriented and from structured through to formal. I argue that two main mistakes are now made. One is to assume that one approach should be used in preference to the others. The other is to ignore or treat as separate the actual elicitation, specification and development process - i.e. the project life cycle.
Models are representations of a subset of reality.
A model may usefully contribute aesthetic or technical views. It is only in computing that we seem obsessed with the idea that one type of model should be used. Computer projects are frequently performed by and for people who have never before participated in a successful application of computing to the particular environment of that type. A development project is itself a system and its components can be viewed as subsidiary developments. These are intersecting Viewpoints of a development process and they intersect with Viewpoints inherent in the requirement for the system being developed.