What is "abhutaparikalpa"

Abhutaparikalpa is a concept which was developed by the Yogacara/Vijnanavada school of Buddhism with regard to definitions of reality identifying it as the dependent nature among the three natures postulated, and is described as neither empty nor not empty by adopting a neither nor position, that it is both existent and not existent. As parantantrasvabhava it exists as such but does not exist as it appears when affected by the 'subject-object duality' of parikalpitasvbhava freed from which it is the perfect nature of parinispannasvabhava. This concept is refuted by Advaita Vedanta in the context of the Buddhist concept of 'momentary existence'.