RT-11 command language had many features (such as commands and device names) that can be found later in the DOS line of operating systems which heavily borrowed from RT-11. The CSI form expected input and output filenames and options ('switches' on RT-11) in a precise order and syntax. The command-line switches were separated by a slash ("codice_1") rather than the dash ("codice_2") used in Unix-like operating systems. All commands had a full form and a short one to which they could be contracted. For example, the RENAME command could be contracted to REN.