SAP: Best practice for SAP message output in non-SAP-GUI contexts
Imagine you see an error message in WebUI or in some other interface. You manage to identify the message class and number, go to SE91, do a Where-used and find - nothing. The reason is that either Where-used was not updated correctly or (most likely) somebody did not both to use the message command to output the message but just hardcoded the message ID, number and type.