A cautionary signal indicating the need for careful attention or moderate concern, but not immediate danger.
From auto racing and maritime signaling where yellow flags indicate caution - proceed but with care (early 1900s). Extended to general business use as traffic light metaphors became widespread in project management and risk assessment.
Yellow flag occupies the perfect middle ground in our risk communication - more serious than 'keep an eye on it' but less alarming than 'red flag.' It's the Goldilocks of warning signals, allowing us to express measured concern without triggering panic.
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