A Mantra consists of certain letters arranged in a definite sequence of sound of which the letters are the representative sequence of sound of which the letters are the representative signs. To produce the designed effect, the Mantra must be intend in the proper way according to both sound (Vani) and rhythm (Svar); for these reasons a Mantra ceases to be such when translated and becomes a mere sentence. By Mantra the sought for Devata appears and by success (Sidda) therein vision is had of the three worlds. As the Mantra is in fact Devata, by practice of this is known and no amount of theoretical knowledge will do. Not merely do the rhythmical vibrations of the sheaths of the worshipper but there form the image of the Devata appears.
The mantra of the Lingayaths is “Namha Shivaya” and is called Panchaxari on account of its having five syllables. With Om ( ) prefixed, it becomes Shadaxarimantra. The mantra is expressive of Shiva and on that account is identical with Shiva, just as a predicate is identical with the subject.
The practice of the Mantra leads to salvation of Moksha. With Om prefixed to it the mantra becomes Shadakshar mantra (of six syllables). Om is Pranava and expresses Parashiva. Om is made up of a, u, m’ and the three express the trinity of powers (Iccha, Jnana, Kriya), which are in turn identical with Satt, Chitt and Anand, The three positive qualities of Parabrahman according to Vedanta. The three powers are the three creative energies. The energy (Nada) in Sadakhatatva springs from Shiva-Shakti-Tattava and solidifies itself (Ghnibhavati) as the creative power of the Lord (Bindu or IshavarTattva) manifesting in the trinity of creative energies. Om then stands for the most general aspect of what which is the source of all, namely Parashiva.
The Panchakshari Mantra (Namha Shivaya) is but an extended form of Om, i.e. Om elaborates or explicates itself in the form of “Namha Shivaya.”
 From the book "Vachana", pub: Basava Samiti Bangalore 2012.