・ Unequivocal (U): the evidence that is beyond reasonable doubt and includes findings that are factual, directly reported or observed, and is not open to challenge.

・ Credible (C): evidence that, while interpretative, is plausible in light of the data and theoretical framework. Conclusions can be logically inferred from the data but, because the findings are essentially interpretive, these conclusions are open to challenge.

・ Unsupported (Us): when none of the other level descriptors apply and when, most notably, findings are not supported by the data.