represented, therefore, by a diacritical sign in the form of a dot, a drop, or a small circle (Skt.: bindu; Tib.: thig-le), i.c., by the symbol of unity, o totality, of the absolute
Govinda argues that the diacritical mark (bindu) is not merely a phonological modifier but the graphic embodiment of absolute unity, transforming the sounds it qualifies into psychic and mantric vibrations.
, Foundations of Tibetan Mysticism, 1960thesis