Maximum permissible errors and measurement uncertainties in measurment instrument characteristics evaluations

Different meanings would appear when measurement uncertainty is used to represent the characteristics of measurment instruments in the production design and purchase.According to the definition,measurement uncertainty is a parameter related to the result of a measurement.And the practical measurement data show that different measurement uncertainties may be obtained when the reproducibility measurement of the same parameter was implemented in the same type of instrument.So the measurement uncertainty is not suitable for representing the characteristics of measurment instruments.When measurement uncertainty is used as a technical parameter of reference material and single parameter of measurment or verifying instruments,the authors have shared their own understandings.