Content of message text

Whenever possible, tell users exactly what has happened and what they can do to remedy the situation.

The following example shows how cause and recovery information can improve a message:

Original  Message:   Bad arg

Revised Message:   Specify year as a value between 1 and 9999.

The message Bad arg does not help users much; whereas the message Do not specify more than 2 files on the command line tells users exactly what they must do to make the command work. Similarly, the message Line too long does not give recovery information to users. The message Line cannot exceed 20 characters provides the missing information.