Systemwide run-control files are a design tactic that can be used on almost any operating system, but dotfiles are rather more difficult to map to a non-Unix environment. The critical thing missing from most non-Unix operating systems is true multiuser capability and the notion of a per-user home directory. DOS and Windows versions up to ME (including 95 and 98), for example, completely lack any such notion; all configuration information has to be stored either in systemwide run-control files at a fixed location, the Windows registry, or configuration files in the same directory a program is run from. Windows NT has some notion of per-user home directories (which made its way into Windows 2000 and XP), but it is only poorly supported by the system tools.