Or is this like khregs chod? This occurs a lot, e.g. in one Vimalamitra khrid yig (II. 19. tshi: A Guide Text on the Direct Perception of the Unsurpassed Exceedingly Secret Great Perfection (rdzogs pa chen po yang gsang bla na med pa chos nyid mngon sum gyi khrid yig) (353-392) It is a kind of emptiness meditation just to let be, and realize the wisdom of awareness.