The following is an example of how IBM writes error messages. Notice the words and phrasing as well as how the alert categories are explained.
Error Message
There is no value specified for the User ID.
Explanation
You must specify a value for the user ID.
Alert Category
Similar events are grouped in categories. The alert category is in the following format:
Severity – device component
Severity is one of the following severity levels:
· Critical: A key component in the server is no longer functioning.
· Warning: The event might progress to a critical level.
· System: The event is the result of a system error or a configuration change.