// calculate the datapoint quality
// this is protected because generally the client should never call this function.
// this should be triggered automatically upon changes on related attributes/parameters
private int update_quality()
{
CosDpQualityEnum newQuality = CosDpQualityEnum.QualityBad;
// determine the datapoint quality. store the new quality in newQuality
if (sourceValue_.quality == CosDpQualityEnum.QualityBad)
{
// if source quality is bad, always set to bad.