exdatum

Exdatum is a term that appears only sporadically in English-language technical writing and does not have a widely accepted standard definition. It is typically formed from the Latin prefix ex- (out of, from) and datum (a given piece of information), and is usually read as “an external datum” or “data from outside a framework.”

In practice, exdatum is used in some niche discussions to denote data that originates outside the model, experiment, or dataset being considered. For example, it may refer to a reference measurement used to calibrate or validate a system, or to an external data point used to align results with an independent source. In fields such as surveying, geodesy, or design, there are related concepts like external datum or external reference datum, though exdatum itself is less common and its exact meaning can vary by author and domain.

Because there is no universal definition, readers should interpret exdatum from the context in which it appears. When encountered, it is prudent to determine whether the term refers to an external reference point, an externally supplied dataset, or a calibration datum as intended by the author.

Overall, exdatum remains a non-standard term whose interpretation is context-dependent, rather than a fixed concept in established reference works. See also datum, data, external datum, reference datum, and calibration.