How we research

Every page gives a symbol’s meaning and shows where it comes from. This is how a page gets there.

What a page will and won’t tell you

A page says what a symbol means. It doesn’t tell you what to do about it. Meanings come from the standard that defines the symbol wherever there is one, such as ISO 3758 for care labels or the U.S. Manual on Uniform Traffic Control Devices for road signs.

• Hazard symbol pages name the hazard class and point to the product’s safety data sheet and label.
• Dashboard light pages say which system a light relates to and point to the vehicle’s owner’s manual.
• Road sign pages give the sign’s standard meaning. Rules vary by state and country, and a page isn’t legal advice.
• Drawing symbol pages explain what a symbol represents. They aren’t instructions for doing the work.

Where a garment’s label, a drawing’s own legend or a manufacturer says something different, that takes precedence.

Sources first

Each page starts from published sources. For every statement on a page we record the passage that supports it, word for word, with the source, its publisher and where the passage appears. Two independent sources per symbol is the aim. Sources are listed at the foot of each page.

When a page’s research is prepared, a script fetches every source again and checks that each recorded passage appears in it. A statement no recorded passage supports is cut, however well known it seems.

Written with AI assistance, reviewed by a person

Research and first drafts are done with the help of an AI model, Anthropic’s Claude. It finds candidate sources, records the passages and proposes the text. It cannot publish anything.

A person then reads every page against its recorded passages before it goes live. Their name and the date of the review appear at the foot of the page, as “Last reviewed”.

Kept up to date

Every page is reviewed again at least once a year, and sooner when a standard it depends on changes. Each review updates the date on the page.

Corrections

Every symbol page has a “Report a problem” link. Reports go straight to the editor; corrections are made on the page and it is reviewed again. You don’t need to give an email address.

Advertising

The sites carry advertising. Advertisers have no say in what a page says. See Privacy for what the sites collect.