In a style originating in the Digital Equipment Corporation line of operating systems (OS/8, RT-11, TOPS-10, et cetera), Windows, DOS, some CP/M programs, OpenVMS, and OS/2 all use the slash to indicate command-line options. For example, the command is understood as using the command dir ("directory") with the "wide" option. Notice that no space is required between the command and the switch; this was the reason for the choice to use backslashes as the path separator since one would otherwise be unable to run a program in a different directory.