Time validity of data is information about which period a given value belongs to. Without it, every specific data point – a rate, a deadline, a price, a limit – becomes incorrect once it changes, while the text still looks just as trustworthy as before. For generative search engines this matters: when sources contradict each other, they favour the one that is clearly dated and more recent. In practice this means stating the validity directly next to the data, not just as the article's publication date, using a formulation such as figure valid for the given period. For legislative and rate-related topics, add a link to the source where the reader can verify the current state. If a figure has changed, do not remove the old value without a trace – state what applied before and from when the new one applies, which makes the page a more precise source than the competition.
See also: Content freshness signal, QDF – Query Deserves Freshness, Numerical data and units.
