O is for Om
Om is used during meditation.*
Om is a holy word used in the beginning of many prayers. Om is also used to set a tune for meditation. We also think that Om is like the Navkar Mantra**.
By paying attention to one word, Om, we are paying respect to Arihants, Siddhas, Acharyas, Upadhyayas, and Monks and Nuns.
* deep prayer
** look under N