DOS messages can be divided into two groups: general error messages and device error messages. The three types of general DOS messages are as follows:
Error messages—. These messages indicate that DOS has encountered a problem with a command or with the syntax you used. Execution stops when DOS displays an error message.
Warning messages—. These messages tell you that the next action you take might cause unwanted changes to files or to your system; they often include a prompt, which enables you to select an action.
Information messages—. These messages display needed information about your system's operation or your DOS version's performance. ...