If you create the single screen for the infotype using transaction PM01 Enhance Infotypes, the system prepares the flow logic.
The flow logic of infotypes within the standard system usually follows this pattern.
Action PBO
PROCESS BEFORE OUTPUT.
MODULE BEFORE_OUTPUT.
MODULE get_header_subscreen.
CALL SUBSCREEN subscreen_header INCLUDING header_prog header_dynnr.
MODULE Pnnnn.
MODULE get_t582c_subscreen.
CALL SUBSCREEN subscreen_t582c INCLUDING subscr_prog subscr_dynnr.
MODULE HIDDEN_DATA.
You can carry out infotype-specific initialization procedures within PBO module
Pnnnn . They enable you, for example, to fill the screen fields stored in structures Qnnnn and Znnnn .
If wage types are valuated indirectly, amount field

You must not change PBO modules
BEFORE_OUTPUT and HIDDEN_DATA.Action PAI
PROCESS AFTER INPUT.
MODULE EXIT AT EXIT-COMMAND.
CHAIN.
FIELD Pnnnn-feld1,...
MODULE INPUT_STATUS ON CHAIN-REQUEST.
ENDCHAIN.
PAI module
INPUT_STATUS must be performed if the user makes an entry in a screen field. For this reason, all of the entry fields in the following chain must be counted. PAI module INPUT_STATUS sets internal system statuses: if a value is changed, for example, the infotype record must be stored later.
MODULE PRE_INPUT_CHECKS.
PAI module
PRE_INPUT_CHECKS is used to process the function code before the entry check. If you choose the Exit function, for example, the system stops processing the current single screen.
Once module
PRE_INPUT_CHECKS has been processed, you can carry out your own entry checks or call up your own PAI modules.
FIELD Pnnnn-feld1
SELECT * FROM TABLE Tnnn WHERE feld1 = Pnnnn-feld1
ON INPUT.
FIELD
Pnnnn-feld2 ON INPUT MODULE Modul_feld2 .
At this point, the entry checks must be complete. Once the following process has been carried out, it is no longer possible to change field contents.
PAI module POST_INPUT_CHECKS processes the function code after the entry checks. It also carries out general entry checks. The system checks, for example, whether the start date of the infotype record is before the end date of the record.
All fields on the screen in the following chain must be counted. All of the fields displayed on the single screen must be counted in the following chain.
CALL SUBSCREEN subscreen_t582c.
CHAIN.
FIELD Pnnnn-feld1,RP50M-SPRPS,Tnnn-felda,... .
MODULE POST_INPUT_CHECKS.
ENDCHAIN.

You must not change PAI modules
EXIT , INPUT_STATUS , PRE_INPUT_CHECKS and POST_INPUT_CHECKS .