OUHM

 Ouhm is considered as the mysterious and most powerful compound alphabet which, if pronounced with great concentration and deep philosophical knowledge, can transform one’s atma into the universal body, Bramhah. It symbolises the sentence “Aham Bramhasmi” meaning “I am Bramhah”. In Hindu Philosophy, Atma is the temporary existence which would eventually   get reunited with the Bramhah, the original universal entity. Buddhists venerate Om, the mystic syllable of A-u-m with equal fervor.  The devotees regard it to be too sacred to be uttered aloud, but only to be formed by the lips. 

Adi Buddha at his will proceeded from Ouhm. Ouhm is also pronounced as AUM putting triple letters into one compound letter. In that Aum, omnipresent Adi Buddha resides at and possesses the Tri-ratna or the triple jewels of Buddhism. Another way it is interpreted is as follows:

Adi Buddha became manifest in the greatest Sunyata or void or nothingness as represented by  the letter A. When all was Sunyata, Prajnan or the transcendental knowledge or Adi Dharma was revealed out of Akash which is represented by the letter U.  Then the Vija or the original seed of mantra of Sangha revealed having represented by the letter  M.  Thus the letters A-u-m  or Ohm represent the vija mantra of Buddha. Dharma and Sangha collectively known as Tri-Ratna.