The smallest unit for MAC is Microcent.
Micro = 1/1.000.000
Cent = 1/100
Microcent = (1/100)/1.000.000=1/100.000.000
In practice its probably good to use
1. Machinecoin Microcents
2. (Mac) Microcents
3. (Mac) Microns
4. (Mac) Mic
5. (Mac) µc