IEC TR 62687: Graphical Symbols for Use on Equipment — Vocabulary and Engineering Application

In an increasingly globalized engineering world, graphical symbols serve as the universal language that transcends linguistic barriers. IEC TR 62687 provides a consolidated vocabulary of terms used across IEC, ISO, and ITU publications in the domain of graphical symbols for use on equipment. This Technical Report, first published in 2011 and revised in 2015, collects and harmonizes definitions from dozens of source standards, creating a single reference for engineers, interface designers, and technical writers. This article examines the standard’s structure, key definitions, and practical engineering relevance.

📖 1. Core Terminology and Classification Hierarchy

IEC TR 62687 establishes a clear hierarchical taxonomy of visual communication elements used on equipment. Understanding this hierarchy is essential for anyone involved in product labeling, control panel design, or user interface development. The standard distinguishes several fundamental categories:

Term	Definition	Engineering Application
Graphical symbol	visually perceptible figure with a particular meaning, transmitted independently of language	Control panel labels, equipment markings, function indicators
Icon	Graphical symbol presented on a screen or display	Touchscreen UIs, HMI displays, soft-key labels
Glyph	Recognizable abstract graphic symbol independent of specific design	Font-based symbols, character sets for displays
Pictogram	Simplified pictorial representation to guide people	Public information signs, wayfinding on equipment
Safety sign	Combination of colour, geometric shape, and graphical symbol conveying a safety message	Warning labels, hazard markings, emergency indicators
Signal word	Word calling attention to a hazardous situation (danger, warning, caution)	Product safety labeling per ISO 3864 and ANSI Z535

💡 Engineering Insight: The distinction between “graphical symbol for use on equipment” and “safety sign” is critical for compliance. Graphical symbols per IEC 60417 are for functional information, while safety signs per ISO 3864 follow strict color/shape rules (red circle for prohibition, yellow triangle for warning, blue circle for mandatory action). Mixing these conventions creates confusion and potential liability exposure.

Dynamic and Static Symbols

A particularly important concept introduced in the standard is the dynamic graphical symbol, whose colour and/or appearance changes according to the internal status of the equipment. This concept bridges traditional static markings with modern electronic displays. For example, a power symbol that changes from green (standby) to white (active) to red (fault) is a dynamic graphical symbol — a concept that becomes increasingly relevant as equipment migrates from physical labels to software-rendered interfaces.

🔬 2. Standard Structure and Source Standards

IEC TR 62687 draws its terminology from an extensive network of source standards. Rather than creating new definitions, the Technical Report performs a harmonization function, collecting terms from published standards and annotating them where clarification is needed. The key source domains include:

IEC 60417 series: The master database of graphical symbols for use on equipment, containing over 1,000 registered symbols covering everything from power on/off to medical equipment functions.
ISO 7000 / ISO 7001: Graphical symbols for equipment and public information symbols respectively.
ISO 3864 series: Safety colours and safety signs — defines the colour/shape conventions for hazard communication.
ISO/IEC 10646 / ISO/IEC 9541: Character encoding and glyph identification for digital representation of symbols.
ITU-T Recommendations: Telecommunications-specific pictograms and symbols.

Source Domain	Key Standards	Symbol Count (Approx.)
Electrical/Electronic equipment	IEC 60417 series	1,000+
Public information	ISO 7001	150+
Safety signs	ISO 3864 series	100+
Telecommunications	ITU-T E.121, etc.	50+
General equipment	ISO 7000	4,000+

⚠️ Important Consideration: While IEC TR 62687 provides a unified vocabulary, engineers must always verify the specific requirements of the applicable product standard. A symbol that is acceptable for general industrial equipment may not meet the stricter requirements of medical devices (IEC 60601), aerospace systems, or hazardous location equipment. Always cross-reference the product family standard before finalizing symbol selection.

⚙️ 3. Engineering Application and Design Guidance

The practical value of IEC TR 62687 extends beyond simple vocabulary reference. For design engineers, the standard provides essential guidance on several critical aspects of symbol application:

Language Independence

Graphical symbols must convey meaning with minimal reliance on language. The standard emphasizes that letters and punctuation marks should be avoided as graphical symbol elements. This principle is particularly important for equipment destined for global markets — a well-designed symbol eliminates the need for multilingual labels and reduces the risk of misinterpretation.

✅ Best Practice: When designing a new equipment symbol, follow the “comprehensibility test” methodology from ISO 9186. A symbol is considered acceptable when at least 67% of test subjects correctly guess its meaning without prior training. For safety-critical symbols, the threshold rises to 85%. Always validate symbol designs through user testing rather than relying on intuitive appeal.

Pictogram vs. Abstract Symbol Decision

The standard provides a useful continuum between purely abstract graphical symbols (e.g., the IEC 60417 power symbol) and pictorial representations (e.g., a printer icon that looks like a printer). Abstract symbols require learning but are more compact and scalable across contexts. Pictorial representations are more intuitive but may not translate well across cultures (e.g., a mailbox icon may be unrecognizable in regions with different mailbox designs).

🔴 Common Pitfall: Using colour as the sole means of conveying equipment status is a design error that creates accessibility problems for colour-blind users (approximately 8% of males). IEC TR 62687’s definitions consistently emphasize shape and contrast as primary carriers of meaning. Colour should be redundant — it reinforces the message but is not the only channel. Always pair colour indicators with distinct symbol shapes or text annotations.

❓ Frequently Asked Questions

Q1: Is IEC TR 62687 a mandatory standard or just informative?

IEC TR 62687 is a Technical Report, meaning it is informative rather than normative. However, the source standards it references (IEC 60417, ISO 3864, etc.) are often mandatory when cited by product safety standards. The TR serves as a convenient consolidated reference but does not itself impose requirements.

Q2: How does IEC TR 62687 relate to digital UI/UX design?

The standard directly addresses icons and dynamic graphical symbols, making it relevant to software-based user interfaces on equipment. However, it does not cover purely software UI elements that have no physical equipment counterpart. For general software iconography, additional references like ISO/IEC 11581 (icons for user interfaces) should be consulted.

Q3: What is the difference between a “glyph” and a “graphical symbol”?

A glyph is an abstract graphic symbol independent of specific design — essentially the conceptual identity of a character or symbol. A graphical symbol is the actual visual representation used on equipment. The same glyph can have many different graphical representations (different styles, sizes, rendering technologies) while retaining the same meaning.

Q4: Can I use symbols from IEC TR 62687 directly on my product?

The symbols themselves are defined in their respective source standards, primarily IEC 60417. You must obtain the correct symbol artwork from the official source (the IEC 60417 database at www.graphical-symbols.info). IEC TR 62687 provides the vocabulary and definitions but not the actual symbol graphics.