Common User Access (CUA) is a standard for
user interface
In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine fro ...
s to
operating system
An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs.
Time-sharing operating systems scheduler (computing), schedule tasks for ...
s and
computer program
A computer program is a sequence or set of instructions in a programming language for a computer to Execution (computing), execute. It is one component of software, which also includes software documentation, documentation and other intangibl ...
s. It was developed by
IBM
International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
and first published in 1987 as part of their
Systems Application Architecture. Used originally in the
MVS/ESA
Multiple Virtual Storage, more commonly called MVS, is the most commonly used operating system on the System/370, System/390 and IBM Z IBM mainframe computers. IBM developed MVS, along with OS/VS1 and SVS, as a successor to OS/360. It is unr ...
,
VM/CMS
VM (often: VM/CMS) is a family of IBM virtual machine operating systems used on IBM mainframes System/370, System/390, zSeries, System z and compatible systems, including the Hercules emulator for personal computers.
Design
The heart o ...
,
OS/400
IBM i (the ''i'' standing for ''integrated'') is an operating system developed by IBM for IBM Power Systems. It was originally released in 1988 as OS/400, as the sole operating system of the IBM AS/400 line of systems. It was renamed to i5/OS in 2 ...
,
OS/2
OS/2 is a Proprietary software, proprietary computer operating system for x86 and PowerPC based personal computers. It was created and initially developed jointly by IBM and Microsoft, under the leadership of IBM software designer Ed Iacobucci, ...
and
Microsoft Windows
Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...
operating systems, parts of the CUA standard are now implemented in programs for other operating systems, including variants of
Unix
Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...
. It is also used by
Java
Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...
AWT and
Swing.
Motivations and inspirations
IBM wanted a standard way to interact with
text-based user interface
In computing, text-based user interfaces (TUI) (alternately terminal user interfaces, to reflect a dependence upon the properties of computer terminals and not just text), is a retronym describing a type of user interface (UI) common as an ear ...
software, whether the screen was a
dumb terminal
A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. Most early computers only had a front panel to input or display ...
connected to a mainframe or a
PS/2 with
VGA graphics. CUA was a detailed specification and set strict rules about how applications should look and function. Its aim was in part to bring about harmony among
DOS
DOS (, ) is a family of disk-based operating systems for IBM PC compatible computers. The DOS family primarily consists of IBM PC DOS and a rebranded version, Microsoft's MS-DOS, both of which were introduced in 1981. Later compatible syste ...
applications, which until then had independently implemented different user interfaces.
For example, to open a file:
* In
WordPerfect
WordPerfect (WP) is a word processing application, now owned by Alludo, with a long history on multiple personal computer platforms. At the height of its popularity in the 1980s and early 1990s, it was the market leader of word processors, disp ...
, the command to open a file was , .
* In
Lotus 1-2-3
Lotus 1-2-3 is a discontinued spreadsheet program from Lotus Software (later part of IBM). It was the first killer application of the IBM PC, was hugely popular in the 1980s, and significantly contributed to the success of IBM PC-compatibles ...
, a file was opened with (to open the menus), (for File), (for Retrieve).
* In
Microsoft Word
Microsoft Word is a word processor program, word processing program developed by Microsoft. It was first released on October 25, 1983, under the name Multi-Tool Word for Xenix systems. Subsequent versions were later written for several other platf ...
, a file was opened with (to open the menus), (for Transfer), (for Load).
* In
WordStar
WordStar is a discontinued word processor application for microcomputers. It was published by MicroPro International and originally written for the CP/M-80 operating system (OS), with later editions added for MS-DOS and other 16-bit computing, ...
, (to get to the ''Opening Menu''), followed by .
* In
emacs
Emacs (), originally named EMACS (an acronym for "Editor Macros"), is a family of text editors that are characterized by their extensibility. The manual for the most widely used variant, GNU Emacs, describes it as "the extensible, customizable, s ...
, a file is opened with + followed by + (for find-file).
* In
vi, use to allow commands, then to open the file browser.
was often the
help key (such as
Volkswriter (1982)
), but in WordPerfect, help was on instead. Some programs used to cancel an action, while some used it to complete one; WordPerfect used it to repeat a character. Some programs used to go to the end of a line, while some used it to complete filling in a form. sometimes toggled between overtype and inserting characters, but some programs used it for "paste".
Thus every program had to be learned individually and its complete user interface memorised. It was a sign of expertise to have learned the UIs of dozens of applications, since a novice user facing a new program would find their existing knowledge of a similar application either of no use or actively a hindrance to understanding as learned behavior might need to be unlearned for the new application.
The detailed CUA specification, published in December 1987, is 328 pages long. It has similarities to
Apple Computer
Apple Inc. is an American multinational corporation and technology company headquartered in Cupertino, California, in Silicon Valley. It is best known for its consumer electronics, software, and services. Founded in 1976 as Apple Computer Co ...
's detailed
human interface guidelines
Human interface guidelines (HIG) are software development documents which offer application developers a set of recommendations. Their aim is to improve the experience for the users by making application interfaces more intuitive, learnable, and ...
(139 pages).
The Apple HIG is a detailed book specifying how software for the 1984
Apple Macintosh
Mac is a brand of personal computers designed and marketed by Apple Inc., Apple since 1984. The name is short for Macintosh (its official name until 1999), a reference to the McIntosh (apple), McIntosh apple. The current product lineup inclu ...
computer should look and function.
When it was first written, the Mac was new, and
graphical user interface
A graphical user interface, or GUI, is a form of user interface that allows user (computing), users to human–computer interaction, interact with electronic devices through Graphics, graphical icon (computing), icons and visual indicators such ...
(GUI) software was a novelty, so Apple took great pains to ensure that programs would conform to a single shared look and feel. CUA had a similar aim, but it faced the more difficult task of trying to impose this retroactively on an existing, thriving but chaotic industry, with the much more ambitious goal of unifying all UI, from personal computers to minicomputers to mainframes; and supporting both character and GUI modes, and both batch and interactive designs. By comparison, the Apple HIG only supported interactive GUI on a standalone personal computer. CUA also attempted to be a more measurable standard than the Apple HIG and had large sections formatted as checklists to measure compliance.
Description
The CUA contains standards for the operation of elements such as
dialog box
In computing, a dialog box (also simply dialog) is a graphical control element in the form of a small window that communicates information to the user and prompts them for a response.
Dialog boxes are classified as " modal" or "modeless", dep ...
es,
menus and
keyboard shortcut
In computing, a keyboard shortcut (also hotkey/hot key or key binding) is a software-based assignment of an action to one or more keys on a computer keyboard. Most Operating system, operating systems and Application software, applications come ...
s that have become so influential that they are implemented today by many programmers who have never read the CUA.
Some of these standards can be seen in the operation of Windows itself and DOS-based applications like the MS-DOS 5 full-screen
text editor
A text editor is a type of computer program that edits plain text. An example of such program is "notepad" software (e.g. Windows Notepad). Text editors are provided with operating systems and software development packages, and can be used to c ...
edit.com. CUA hallmarks include:
* All operations can be done with either the
mouse
A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus'' ...
or the
keyboard;
* If applicable to the page/screen in question provides a refresh function;
* Menus are activated/deactivated with the key;
* Menus are opened by pressing the key plus the underlined letter of the menu name;
* Menu commands that require parameters to proceed are suffixed with an
ellipsis
The ellipsis (, plural ellipses; from , , ), rendered , alternatively described as suspension points/dots, points/periods of ellipsis, or ellipsis points, or colloquially, dot-dot-dot,. According to Toner it is difficult to establish when t ...
("…");
* Options are requested using secondary windows (often called dialog boxes);
* Options are divided into sections using notebook tabs;
* Navigation within fields in dialog boxes is by cursor key; navigation between fields is by pressing the key; + moves backwards;
* Dialog boxes have a 'Cancel' button, activated by pressing the key, which discards changes, and an 'OK' button, activated by pressing , which accepts changes;
* Applications have
online help
Online help is a form of user assistance that provides topic-oriented, procedural or reference information designed to assist in using a software application, web application or operating system. Online help linked to the application's state ( ...
accessed by a Help menu, which is the last option on the menu bar; context sensitive help can be summoned by ;
* The first menu is to be called 'File' and contains operations for handling files (new, open, save, save as) as well as quitting the program; the next menu 'Edit' has commands for undo, redo, cut, copy, delete, paste commands;
* The
Cut
Cut or CUT may refer to:
Common uses
* The act of cutting, the separation of an object into two through acutely directed force
** A type of wound
** Cut (archaeology), a hole dug in the past
** Cut (clothing), the style or shape of a garment
** ...
command is +;
Copy is +;
Paste is +;
* The size of a window can be changed by dragging one of the 8 segments of the border.
CUA not only covers DOS applications, but is also the basis for the Windows Consistent User Interface standard (CUI), as well as that for OS/2 applications — both text-mode and the
Presentation Manager Presentation Manager (PM) is the graphical user interface (GUI) that International Business Machines, IBM and Microsoft introduced in version 1.1 of their operating system OS/2 in late 1988.
History
Microsoft began developing a graphic user inter ...
GUI — and IBM mainframes which conform to the
Systems Application Architecture.
CUA was more than just an attempt to rationalise DOS applications — it was part of a larger scheme to bring together, rationalise and harmonise the overall functions of software and hardware across IBM's entire computing range from microcomputers to mainframes.
The third edition of CUA took a radical departure from the first two by introducing the
object-oriented
Object-oriented programming (OOP) is a programming paradigm based on the concept of '' objects''. Objects can contain data (called fields, attributes or properties) and have actions they can perform (called procedures or methods and impleme ...
workplace
A workplace is a location where someone works, for their employer or themselves, a place of employment. Such a place can range from a home office to a large office building or factory. For industrialized societies, the workplace is one of the ...
. This changed the emphasis of the user's interactions to be the data (documents, pictures, and so on) that the user worked on. The emphasis on applications was removed with the intention of making the computer easier to use by matching users' expectations that they would work on documents using programs (rather than operating programs to work on documents). (See also
object-oriented user interface
In computing, an object-oriented user interface (OOUI) is a type of user interface based on an object-oriented programming metaphor, and describes most modern operating systems ("object-oriented operating systems") such as MacOS and Unix. In an OOU ...
.)
Influence
CUA strongly influenced the early
Microsoft Windows
Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...
operating system during the period of joint IBM and Microsoft cooperation on OS/2 Presentation Manager. But later releases of IBM's CUA documents were not used for Microsoft products, and so CUA became less significant in the Windows environment. For instance, the
Start menu was introduced. Most of the standard keystrokes and basic GUI widgets specified by the CUA remain available in Windows. The well-known combination for closing a window, , stems from CUA.
CUA never had significant impact on the design of
Unix
Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...
terminal (character-mode) applications, which preceded CUA by more than a decade. However, all major Unix GUI environments/toolkits, whether or not based on the
X Window System
The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems.
X originated as part of Project Athena at Massachusetts Institute of Technology (MIT) in 1984. The X protocol has been at ...
, have featured varying levels of CUA compatibility, with Motif/
CDE explicitly featuring it as a design goal. The current major environments,
GNOME
A gnome () is a mythological creature and diminutive spirit in Renaissance magic and alchemy, introduced by Paracelsus in the 16th century and widely adopted by authors, including those of modern fantasy literature. They are typically depict ...
and
KDE
KDE is an international free software community that develops free and open-source software. As a central development hub, it provides tools and resources that enable collaborative work on its projects. Its products include the KDE Plasma gra ...
, also feature extensive CUA compatibility. The subset of CUA implemented in
Microsoft Windows
Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...
or
OSF/Motif is generally considered a
de facto standard
A ''de facto'' standard is a custom or convention that is commonly used even though its use is not required.
is a Latin phrase (literally " of fact"), here meaning "in practice but not necessarily ordained by law" or "in practice or actuality, ...
to be followed by any new Unix GUI environment.
See also
*
Table of keyboard shortcuts
In computing, a keyboard shortcut is a sequence or combination of keystrokes on a computer keyboard which invokes commands in software.
Most keyboard shortcuts require the user to press a single key or a sequence of keys one after the other. Oth ...
References
* IBM, Systems Application Architecture: Common User Access: Panel Design and User Interaction, Document SC26-4351-0, 1987.
* IBM, Systems Application Architecture: Common User Access: Advanced Interface Design Guide, Document SC26-4582-0, 1990.
* IBM, Systems Application Architecture: Common User Access: Basic Interface Design Guide, Document SC26-4583-0
1992. (Partial archive)
* IBM, Systems Application Architecture: Common User Access: Guide to User Interface Design, Document SC34-4289-00 199
* IBM, Systems Application Architecture: Common User Access: Advanced Interface Design Reference, Document SC34-4290-00 199
*
External links
* , by
Richard E. Berry,
IBM Systems Journal
''IBM Journal of Research and Development'' is a former, peer-reviewed bimonthly scientific journal covering research on information systems.
This Journal has ceased production in 2020.
According to the ''Journal Citation Reports'' in 2019, the jo ...
, Volume 27, Nº 3, 1988
Citations This link is down, PDF still available at: https://web.archive.org/web/20070927082756/http://www.research.ibm.com/journal/sj/273/ibmsj2703E.pdf
* , by Richard E. Berry,
Cliff J. Reeves, IBM Systems Journal, Volume 31, Nº 3, 1992
Citations
* , by Richard E. Berry, IBM Systems Journal, Volume 31, Nº 3, 1992
Citations
IBM BookManager SAA CUA bookshelf1992
CUA Window Emulation for SlickEdit - A table of CUA-based hotkeys provided by a
SlickEdit mode
{{OS/2
Common User Access
Human–computer interaction
User interface techniques
Common User Access