S. No	No. of Sources	No. of Switches	No. of Output Levels
S. No	No. of Sources	No. of Switches	Symmetrical	Asymmetrical Binary	Asymmetrical Tertiary
1.	01	02	03	03	03
2.	02	06	05	07	09
3.	03	10	11	15	27
4.	04	14	19	31	81