You are right: NTFS exclusively runs on UCS-2, now "UTF-16 without validation". Back in the 1980s "Unicode" referred to a way to represent the ISO standard "Universal Character Set", i.e. UCS-2, instead of being synonymous to the entire character set like today. The wisdom of i18n back then was to use "Unicode" text encoding because it covered the known universe of writing. Qt made a similar choice.