CUA - Common User Access
Common User Access (CUA) is a set of IBM guidelines for designing consistent user interfaces, primarily for character-based terminals like the 3270, prevalent in mainframe environments. It aims to standardize the look, feel, and interaction methods across different applications, improving user productivity and reducing learning curves.
Key Characteristics
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- Standardized UI Elements: Defines common elements such as menu bars, action bars, entry fields, scrollable areas, and message lines, ensuring a predictable layout for 3270 screens.
- Function Key (PF Key) Usage: Prescribes consistent assignments for Program Function (PF) keys (e.g.,
PF3for Exit,PF7/PF8for scrolling,PF1for Help) across applications to standardize navigation. - Hierarchical Menu Structures: Encourages the use of nested menus and panels to organize functions logically, allowing users to navigate through options systematically and find desired tasks.
- Character-Based Interaction: Primarily designed for text-based, block-mode terminals (e.g., IBM 3270), where user interaction involves entering data into specific fields and pressing
Enteror PF keys to submit actions. - Consistency Across Applications: The core goal is to make diverse applications, from system utilities like ISPF to custom business applications, behave similarly, reducing user training time and potential errors.
Use Cases
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- ISPF Panels and Dialogs: The IBM Interactive System Productivity Facility (ISPF) is a prime example, with its extensive use of CUA guidelines for its menus, data entry panels, and utility screens, providing a consistent user experience for developers and system administrators.
- CICS Transaction Screens: Many CICS (Customer Information Control System) applications, especially those developed with BMS (Basic Mapping Support), adhere to CUA principles for their user interaction screens, ensuring familiarity for operators.
- TSO/E Command Processors: Applications invoked from the TSO/E (Time Sharing Option/Extensions) command line often present CUA-compliant interfaces for user input and display, integrating seamlessly with the interactive environment.
- Custom Application Development: COBOL, PL/I, or Assembler programs that interact directly with 3270 terminals via services like MVS
GETandPUTmacros or CICS BMS typically implement CUA guidelines for their user interfaces to enhance usability.
Related Concepts
CUA is foundational to the user experience on the mainframe, particularly for interactive applications. It is most visibly implemented within ISPF, which serves as the primary interactive development and system management environment for z/OS, providing a consistent CUA-compliant interface for numerous utilities. It heavily influences how 3270 terminals are used, dictating the layout and interaction model for screens displayed on these devices. Adherence to CUA principles simplifies the development of user-friendly applications using languages like COBOL or PL/I by providing a blueprint for screen design and navigation.
- Strict Adherence for New Development: When designing new interactive mainframe applications, strictly follow CUA guidelines to ensure consistency with existing system utilities and reduce the learning curve for users.
- Consistent PF Key Assignments: Always assign PF keys according to CUA standards (e.g.,
PF3for Exit/Return,PF1for Help,PF7/PF8for scrolling) to maintain predictability across all applications. - Clear and Concise Panel Layouts: Design panels with clear labels, logical grouping of fields, and appropriate use of message areas to guide users effectively and minimize confusion on 3270 screens.
- Provide Context-Sensitive Help: Implement
PF1(Help) to offer context-specific assistance for the current screen or field, enhancing usability and reducing reliance on external documentation. - Test User Experience: Conduct thorough user testing to ensure that the application's interface is intuitive, efficient, and truly benefits from CUA principles, rather than just technically complying.