Table 1. gives the complete alphabet. It is based on the Paniniya 14 Māheshwar sūtras. A detailed study has been given by Dr. Vidhātā Mishrā  in a critique based on the Śikśā and Prātiśākhya of the four Vedas. These ancillary texts were taught to the ancient śisya or students as prerequisite to the chanting of the Vedas.
svah+ādityah bhavati – su aranah , su iranah , svrtah rasān,
svrtah bhasam jyotisam, svrtah bhāsā+ity vā. etain dhyauh+vyākhyātā.
svar is the name of the sun – it stands alone, dispersing darkness, it is the heavenly resonance, it lights up the luminaries or the other planetary bodies. svar is the shining light. This explains dhyauh – the celestial region, and its origin from the root word div, which means to be bright from within.
Now, there are two types of bodies in the Universe viz. (a) those that shine and emanate energy themselves and (b) those that reflect light that comes from others – they are themselves ‘dark matter’. In fact the scientists are estimating the ‘dark matter’, which also includes the ‘black-holes’, as far more than the visible matter.