In these lines, you declare explicit error messages for the controls written with specific code. Before generating the error message file, you must indicate this Program in the Comment field of the Overview tab of the transaction Data Structure.
The controls coded on the Data Element calls in Data Structures are the only ones that trigger the automatic generation of error messages. For all the errors that are detected by other controls, error messages must be defined explicitly.
Moreover, if this line is not correct, this column also displays an error or warning symbol, depending on the severity of the error. A hover help indicates the source of the error.