ANSI 4.10.4.5 The contents and mode of execution of the string by the system function
The system function executes an internal operating system command, or an .EXE, .COM (.CMD in Windows NT) or .BAT file from within a C program rather than from the command line.
The system function finds the command interpreter, which is typically CMD.EXE in the Windows NT operating system or COMMAND.COM in Windows 95. The system function then passes the argument string to the command interpreter.