The range within which, at the given level of confidence, the actual value resides. For example, a nominal value (from the context Observation.value) of 4.3 may be reported, but this extension may be used to indicate that the reporting device is only 95% confident that the actual value is in the range of 3.1 to 5.5.

The reported value, if present, should be precise enough to reflect the confidence interval. For example, a nominal quantity of 3.2 kg with a confidence interval of [3.21, 3.27] kg would be nonsensical. On the other hand, a reported value of 3.24 kg with a 95% confidence interval of [3.21, 3.27] kg would indicate a 95% confidence that the actual value is in that range.

The reported value need not be at the center of the confidence interval; for example, if the values don't follow a normal distribution. The context Observation.value SHOULD be present when this extension is used, due to the risk that systems unfamiliar with (or ignoring) this extension may be unable to process a valueless quantity.

The interval range low and high units are usually the same as the reported value's units. Confidence interval range low and high units SHOULD be provided for clarity; if omitted, they are implied to be the same as the reported value's units.