Wavy lines, or a dish beneath them, indicating microwave use.
Also known as: Microwave symbol, Wavy lines symbol, Microwaveable symbol
Wavy lines mark a container as suitable for microwave use. There is no standard for it: the drawing varies between manufacturers, and it is the manufacturer's assurance rather than a certification.
Is not a standardised symbol. No body defines it, its drawing varies between manufacturers, and its presence is the manufacturer's own assurance rather than a certification — so the absence of the mark does not reliably mean the object is unsuitable, and its presence is not a guarantee.
Stated first rather than as a footnote, because it is the most useful thing to know about the mark. Check the manufacturer's own instructions where it matters.
Contexts: Packaging
Indicates that a container is intended to be used in a microwave oven, usually drawn as two or three horizontal wavy lines, sometimes above a dish.
Contexts: Packaging
Is often crossed through or shown inside a barred circle to mean the opposite — that the container must not be microwaved, most commonly because it contains metal.
Contexts: Packaging
Concerns the container rather than the food: a microwave-safe dish will not be damaged by the process, which is a different question from whether the food inside heats safely or evenly.
Contexts: Packaging
Two or three horizontal wavy lines stacked one above another, sometimes drawn above a shallow dish shape.
Both appear on the base of the same container. This one is about heating and is not standardised; the glass and fork is about the material and is defined in law.