SAP Basis Administration, Functional and ABAP Programming Reference Books
Basis - Message Class - System Message

Configure System Messages

For example, when a user blocks himself out and receives a message :

"User blocked. Contact system administrator"

You can open a repair and change the message in Message class 00. 

This can be done in transaction SE91 - Message Maintenance.

Messages allow you to communicate with the users from your programs. 

They are mainly used when the user has made an invalid entry on a screen. 

To send messages from a program, you must link it to a message class. 

Each message class has an ID, and usually contains a whole set of message. Each message has a single line of text, and may contain placeholders for variables (e.g. & & & - three variables). 

All messages are stored in table T100

Once you have created a message, you can use it in the MESSAGE statement in a program. 
 

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