You can use additional validation to supplement the existing SAP logic to fit you into your businness needs.
For e.g. to allow postings from company code 0001 to business area AA only.
GGB0 - To maintain the validations
Validation - Enter a validation name e.g. VBUS
Applicaion Area - SAP module e.g. FI
Calling Point - Dependent upon the application area that is selected.
0001 - Document Header - validate enteries at document header, e.g BKPF table
0002 - Line Items - check line item entris within a document, e.g. BSEG table
0003 - Complete Document - check settings for the whole documents.
e.g. Validation step 001
Allowed company code '0001' to post to business area AA only. 'FI00' checks that line item is from FI.
If checks failed, the error message number 14 is displayed to stop the transaction.
Prerequisite
<BSEG> $BUKRS = '0001' AND
<BKPF> $GLVOR = 'FI00'
Check
<BSEG> $GSBER = 'AA'
Message
Type E No. 14 - Business Area not allowed for company 0001
Output fields 1 - BSEG - GSBER 2 - BSEG - BUKRS
3 - 4
OB28 - Define Validations for Posting
CC CallPnt Validation Description Activtn Level
0001 2 VBUS Business Area Validation 1
Activtn Level - 0 - Not Active 1 - Activated 2 - Activated for all except batch input
GGB4 - Manage the activation of all validations in the SAP system.