How to block the requirement (MD04) generated by the item category in a sales order when the customer has attained the credit limit?  The MRP requirements still appear even though the schedule is zero.

You should try and use one of the standard requirements. 

See in transaction "VOFM". 

Under Requirements / Subsequent Functions / Reqs.Availablity. 

Try using routine 103, you may have to tweak if it doesn't work exactly as you'd like. 

For example, you can write a routine 903 because you only wanted this reaction for certain business units. Irregardless, using a routine similar to this will prevent the requirement from appearing in MD04 for orders blocked on credit. 

Code: 
DATA: W_ZSDCRD TYPE ZSD_CREDITBLCK. 
DATA: W_CMGST LIKE VBUK-CMGST. 

SELECT SINGLE * INTO W_ZSDCRD 
FROM ZSD_CREDITBLCK 
WHERE KKBER = VBAK-KKBER 
AND CTLPC = VBAK-CTLPC. 

IF SY-SUBRC = 0 AND VBUK-CMGST CA 'B'. 

IMPORT VBUK-CMGST TO W_CMGST FROM MEMORY ID 'CREDIT'. 

IF W_CMGST = SPACE. 
MESSAGE I706(Z1). 
EXPORT VBUK-CMGST TO MEMORY ID 'CREDIT'. 
ENDIF. 
 

*} REPLACE 
*{ INSERT DEVK966908 1 

*} INSERT 
* Read the subsequent function information for the message 
PERFORM FOFUN_TEXT_READ USING GL_FOFUN 
CHANGING FOFUN_TEXT. 
MESSAGE ID 'V1' TYPE 'E' NUMBER '849' 
WITH FOFUN_TEXT 
RAISING ERROR. 
*{ INSERT DEVK966908 2 

*} INSERT 
ENDIF. 
ENDFORM. 

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