The everlasting streams of continuity of the mind, the practices involving Buddha-figures, and the Buddha Bodies, plus the texts that discuss them.
(1) An everlasting stream of continuity. On the causal level, the mental continuum, with its various aspects of Buddha-nature. On the pathway level, the continuity of practices involving Buddha-figures. On the resultant level, the continuity of the various corpuses or bodies of a Buddha. (2) The texts that discuss the above topics.
J Hopkins: continuum.