Some distinguish "delusional" and "non-delusional" forms of ORS. In the delusional type, there is complete conviction that the odor is real. In the non-delusional type, the individual is capable of some insight into the condition, and can recognize that the odor might not be real, and that their level of concern is excessive. Others argue that reported cases of ORS present a spectrum of different levels of insight. Since sometimes the core belief of ORS is not of delusional intensity, it is argued that considering the condition as a form of delusional disorder, as seems to occur in the DSM, is inappropriate. In one review, in 57% of cases the beliefs were fixed, held with complete conviction, and the individual could not be reassured that the odor was non existent. In 43% of cases the individual held the beliefs with less than complete conviction, and was able to varying degrees to consider the possibility that the odor was not existent.