The SI prefixes were invented to avoid decimal points and commas. So, in theory you should write: 470mΩ, instead of 0.47Ω, or 2200pF, instead of 2.2nF. In practice, decimal points are really replaced by the prefixes but not exactly as dictated by the SI. When the unit is obvious it is left out.
I prefer 0R47, 100, 1k, 2k2, etc. for resistors, 2p2, 330p, 4n7, 68n, 2µ2, 10µ, 3300µ for capacitors, and 150n, 2µ2, 330µ, 15m, 10H for inductors.
There are traditional scripts, like 0.01mmF or 10kpF for 10nF, that you can find in vintage schematics. But they are a thing of the past, I guess.