The user interface is the means through which users communicate with the computer system. The Common User Access (CUA) is the definition of user interface components that should be the same across all applications. The definition is based on a set of generally accepted user interface design principles. It is optimized for ease of use and encourages learning by exploring. The fundamental objectives of CUA are:
° Usability and consistency within an application ° Consistency across applications.
When the framework, interaction techniques, and terminology are consistent across a variety of applications, users develop an expectation, or conceptual model, of how an application behaves. If new applications then support the same conceptual model, users can transfer what they have learned to other applications and predict how other applications will behave. This reduces the amount of time users need for learning new applications.
Computer users represent many diverse classes of users ranging from those who use nonprogrammable terminals attached to hosts to those who use personal computers that run either stand-alone or attached to hosts as programmable workstations. To balance the value of consistency between the two environments with the advanced capabilities of the programmable workstation, CUA defines two user interface models: entry and graphical. Where practical, similar user interface components are used across the models to enhance transfer of knowledge.