Nobody uses nF in, say, digital, where the only caps are power supply filter caps and bypass/decoupling caps next to ICs. It's not customary to call a 0.1μF by

Nobody uses nF in, say, digital, where the only caps are power supply filter caps and bypass/decoupling caps next to ICs. It's not customary to call a 0.1μF bypass cap 100 nF. If someone wrote in 100 nF for a decoupling cap, I would tend suspect they are trying to discourage a substitution like 82nF or 150nF and want to find out why. Whereas if it is 0.1μF, I know we can stick in a 0.2μF, if that's what we have on hand, and everything will be fine.