A method of using an oximeter sensor assembly including the steps of detecting light from a light emitting element and storing digital data in a memory associated with the sensor assembly. The stored digital data includes coefficients for use by an oximeter monitor coupled to the sensor assembly to calculate data from the detected light, wherein the coefficients represent a combination of different sensor-specific characteristics, application-specific characteristics, and patient-specific characteristics. Control means including means for processing received information signals in accordance with the equation in response to received coefficients to determine blood oxygen levels is provided.