If the statement FIELD in the event block on PAI is linked with a MODULE statement, then the statement controls the handling of warnings and error messages, which are send in the called module using the statement MESSAGE.
If FIELD is listed outside a processing chain that is introduced with CHAIN, and if a warning or an error message is sent in the dialog module specified after MODULE, then the PAI processing is interrupted and the screen is displayed again without triggering the event PBO. The input field belonging to dynp_field is the only field ready for input on the current screen and can be overwritten by the user . If the value in the input field is changed by the user, the PAI processing is continued after an user action with the first FIELD- or CHAIN-statement that is linked with the dynpro field dynp_field. If the value in the input field is not changed by the user, then the PAI processing is continued again with the current FIELD statement. Previous statements of the PAI event block are not processed again.
If FIELD is listed within a processing chain, introduced by CHAIN, and if a warning or an error message was sent within a module that was called within the processing chain, then the PAI processing is interrupted and the screen displayed again without triggering the event PBO. All input fields of the dynpro fields are ready for input, which are listed within the processing chain after FIELD statements. If the value of at least on of these input fields is changed by the user , then the PAI processing continues after an user action at the first FIELD or CHAIN statement that is linked with one of changed dynpro fields. If none of the input fields is changed by the user, the PAI processing continues again directly at the CHAIN statement of the current processing chain. Previous statements of the PAI event block are not processed again.