A control procedure icon is a small graphical symbol used in user interfaces, diagrams, and documentation to represent a specific control action, such as start, stop, pause, or reset. These icons are standardized enough that users recognize them instantly, and they are essential for clear communication in software, industrial panels, and process flowcharts.
What Is a Control Procedure Icon?
In the broadest sense, a control procedure icon is any icon that conveys an action related to controlling a system or process. This includes media controls (play, pause, stop), power symbols, reset arrows, and safety interlocks. In technical documentation, the same term can refer to a symbol used in a procedure diagram to indicate where a control step occurs—for example, a diamond shape in a flowchart that asks “Is the valve open?”
The key is that the icon is not just decorative; it carries operational meaning. A well-designed control icon reduces the need for text and helps users act quickly and correctly, especially in high-stakes environments like manufacturing or aviation.
Background and Standardization
Icons have been used in control systems since the early days of electrical engineering, but the modern push for standardization began with the International Electrotechnical Commission (IEC) and the International Organization for Standardization (ISO). These bodies publish standards like IEC 60417 for graphical symbols for use on equipment. For example, the familiar “power” symbol (a circle with a vertical line) is defined in IEC 60417 as “standby” or “on/off.”
In software, the rise of graphical user interfaces in the 1980s popularized icons like the floppy disk for “save” and the magnifying glass for “search.” Control-specific icons—such as the triangular play button and the square stop button—were borrowed from audio and video equipment and became universal through their use in operating systems and web players.
How Control Procedure Icons Work in Practice
In a control system, an icon is more than a picture; it is a trigger for an action. When a user clicks or taps an icon, the system executes a predefined procedure. For example:
- A “play” icon (triangle) starts a process or resumes a paused one.
- A “stop” icon (square) halts the process entirely.
- A “pause” icon (two vertical bars) suspends the process without terminating it.
- A “reset” icon (circular arrow) returns the system to its initial state.
In industrial settings, these icons might be physical buttons on a control panel, but they follow the same visual logic. The icon’s meaning is often reinforced by color—green for start, red for stop—but color alone should never be the only indicator, as it is not accessible to all users.
How to Choose the Right Control Procedure Icon
Choosing the wrong icon can cause confusion or even accidents. Here are the factors to consider:
- Familiarity: Use icons the user already knows. Don’t invent a new symbol for “pause” when the two vertical bars are universally understood.
- Clarity: The icon should be simple and readable at the size it will be displayed. A complex icon with fine details will be illegible on a small button.
- Consistency: Use the same icon for the same action throughout your system. If you use a different “stop” icon in one screen, users will be confused.
- Context: Consider the environment. In a medical device, an icon might need to be larger and have a tactile feel; in a mobile app, it must work on a touchscreen.
- Accessibility: Provide text labels or tooltips alongside icons, especially for less common actions. This helps users with visual impairments and those unfamiliar with the icon.
Common Problems and Misconceptions
One common misconception is that icons are universally understood. In reality, cultural differences and context can change their meaning. For instance, a “checkmark” might mean “yes” in the US but “incorrect” in some other countries. Similarly, a “power” icon can mean “on” or “standby,” and users may not know which until they press it.
Another problem is the overuse of icons. When every button has an icon, users can become overwhelmed and miss the critical control. The solution is to prioritize: use icons for the most frequent and important actions, and use text buttons for less critical ones.
Also, beware of the “hamburger” icon (three horizontal lines) for menus—it is widely used but still not understood by a significant portion of the population, especially older users. For control procedures, always test your icons with a sample of your target users.
Comparison: Icons vs. Text Labels
Icons are faster to recognize than text, but they are also more ambiguous. Text labels are explicit but slow to read. The best approach is to combine both: an icon with a text label underneath or a tooltip on hover. This is called a “compound” control.
For example, a “play” button with the word “Play” below it leaves no room for doubt. In safety-critical systems, redundancy is essential—if an icon fails to communicate, the text will save the day.
Cost and Safety Considerations
Designing a custom set of control icons can be expensive, especially if you need to test them for usability and comply with industry standards. However, using open-source icon sets (like Font Awesome or Material Icons) is a low-cost alternative, but you must ensure the icons are licensed for your use and that they meet any regulatory requirements.
Safety is paramount when icons control physical machinery. Always follow the relevant standards (e.g., IEC 60417, ISO 7010 for safety signs) and include safety instructions in the user manual. Never rely solely on an icon to convey a warning—use text and, where necessary, audible alarms.
Alternatives to Traditional Icons
In some contexts, icons are being replaced by other interaction methods:
- Voice control: “Hey device, start the pump” eliminates the need for a visual icon.
- Gesture control: Swiping or tapping patterns can trigger actions without a visible icon.
- Augmented reality: In AR interfaces, icons can be overlaid on the real world, but they still serve the same purpose.
Despite these alternatives, icons remain the most efficient way to communicate a control action in a graphical interface. They are compact, language-independent, and instantly recognizable when designed well.
Template for a Control Procedure Icon Specification
Use this template to document the icons used in your system. Fill in each field for every icon.
| Icon Name | Action | Visual Description | Color | Size (px) | Tooltip Text |
|---|---|---|---|---|---|
Sample (fictional):
| Icon Name | Action | Visual Description | Color | Size (px) | Tooltip Text |
|---|---|---|---|---|---|
| Start | Begin process | Right-pointing triangle | Green | 24 | Start |
| Stop | Halt process | Square | Red | 24 | Stop |
Frequently Asked Questions
What is the difference between a control icon and a regular icon?
A control icon specifically triggers an action or changes the state of a system, while a regular icon might just represent a file, a location, or a concept. For example, a folder icon is not a control; it just shows a directory. But a “delete” icon (trash can) is a control because it performs an action.
Are control procedure icons standardized across industries?
Some are. For example, the play, pause, and stop symbols are nearly universal in media players. However, industrial control icons may vary by manufacturer, though many follow IEC 60417. Always check the standards relevant to your industry.
Can I use emojis as control icons?
Emojis are not recommended for professional control interfaces because their appearance varies across platforms and they are not designed for clear, small-size rendering. Stick to dedicated icon sets that are consistent and scalable.
How do I test if my control icons are effective?
Conduct a usability test with a sample of your target users. Show them the icon without any text and ask what action they think it triggers. If less than 80% give the correct answer, redesign the icon or add a text label.
What should I do if an icon is not understood?
Add a text label next to the icon, or replace the icon entirely with a text button. It is better to be explicit than to have users guess. Also consider using a more conventional icon that users are likely to have seen before.