ISO 7000 and IEC 60417 establish the drawing basics.

 

Geoffrey Peckham

Whether we realize it or not, we come in contact with function and control symbols on a daily basis. Look at your computer monitor, your VCR control, the microwave, the buttons in your car, or the controls of your garden tractor: Function and control symbols are virtually everywhere. It is therefore necessary that we have standards for these symbols, for consistency among products using symbols. Imagine if this were not the case: Manufacturers would make up their own symbols, and consumers would be faced with a visual puzzle every time they rented a car or operated a VCR.

For many years, the committees responsible for ISO 7000 and IEC 60417 (formerly known as IEC 417) collected and registered the symbols developed by various product technical committees within ISO and IEC. The resulting standards have the same title: "Graphical Symbols for Use on Equipment."

To be accepted into these standards, symbols must adhere to design criteria defined in IEC 80416-1, "Basic Principles for Graphical Symbols for Use on Equipment—Part 1: Creation of Graphical Symbols." This standard defines the 75-mm basic pattern (see Figure 1). This pattern serves as a drawing template on which to place the lines, circles, squares, arrows, and other shapes that make up a symbol. Symbols that use this pattern include IEC 5016, Fuse, and IEC 5019, Protective Earth (see Figures 2 and 3).

 

Figure 1. The basic pattern.	Figure 2. IEC 5016, Fuse.	Figure 3. IEC 5019, Protective Earth.	Figure 4. IEC 5108B, Fast Run.

The basic pattern also plays an integral role in defining the actual drawing rules contained in 80416. Examples of such rules include: "The lines of the graphical symbol should be centered on the lines of the basic pattern wherever possible." "Symbol originals should be designed to the largest size possible while ensuring the correct relative and apparent size and shall not extend beyond octagon eight of the basic pattern."

IEC 80416

ISO and IEC formed a joint workgroup, JWG 11, in 1998 to revise what is now a multipart standard (IEC/ISO 80416) on the creation of graphical symbols for use on equipment. This workgroup is made up of experts in the field of graphical symbols, and I was the representative for the United States during 1998 and 1999. It was interesting to take part in this committee's arguments during its first years of existence, because the debate centered on major questions regarding what would be accepted as the standardized line width, the proper use of the grid, and the range of allowable deviations from the standardized drawing rules.

Although immediate comprehension of a function or control symbol is desired, it is not a requirement. The reason for this is that it can be difficult to develop intuitively understood, abstract symbols that are meant to convey an idea. Take, for example, symbol 5108B (see Figure 4). Because it is taken out of context, you may not recognize it. Its official title is "Fast Run; Fast Speed." In practice, we know it as "fast forward," and it appears on VCRs. The first generation of people to use VCRs 20 years ago probably looked at the manual to learn this symbol's meaning. Subsequent generations have learned this symbol either by watching previous generations or through trial and error. Like most symbols contained in ISO 7000 and IEC 60417, this symbol is not, on its own, intuitively understood until it is learned.

The topic of understanding symbols will be revisited in a future column on safety symbols.

Geoffrey Peckham is president of Hazard Communication Systems (Milford, PA), a company specializing in the design and production of product safety labels. For more information, visit http://www.safetylabel.com. Peckham is chairman of the U.S. technical advisory group to ISO TC 145 on graphical symbols. He can be reached at gpeckham@safetylabel.com.

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