Substitution Logic- Very Urgent

Question

Hi,
Background: I never done substitution in past. Customer  wants partial payment, credit memo, debit memo baseline date should be the same with reference to cutomer's original invoice baseline date. e.g.
1. Customer invoice 01/01/2007 and baseline date is 01/01/2007
2. Partial payment 06/10/2007 and baseline date is 01/01/2007
3. Credit memo 09/15/2007 and baseline date is 01/01/2007
To achieve we have user exit to replace the current baseline with original invoice baseline date. This user exit will be assigned to my substitution rule. Before do that i want make sure my substitution rule logic is correct:
I have written following prereqiuest(Formula) in substitution rule in order to meet baseline date.
"BSEG-KOART='D' AND BKPF-BLART='DR,DZ,RK,DZ'"
"AND BSEG-ZFBDT='08'" TRUE
Do you foresee any problem here?. If yes please let know so that i correct it.
Your immediate action is highly appreciated.. I will also assign double points..
Regrds,
Jagadeesan

Answer 1

There is an issue with the logic
1) You want to use this logic for fields at BKPF (Header Level) and also BSEG (Line item Level).. Some times this does not work. You might want to try this out in your instance. The system works best when you have substitution either at a line item level or at a header level . It has an option for substitution for the whole document as well.. but in a lot of cases I tried it ..it did not work.
2) If the fields at both line item and header are avbl to you in your substitution for whole document , then your logic will work. (so the logic that you have given -- functionally it should work) constraint : as described in 1 above.
3) If this does not work ..then i would suggest the following approach
Option A - drop the KOART and the Base line date from your logic and work only with Doc Type + Co Code + Reference Procedure + T Code - since these are all Header level
Option B - Work with some BTE ..go to FIBP.. see if there is some BTE which you can use.
For SD documents there are a number of user exits avbl which modify the values passed from SD to the FI document ..
Hope this helps
Option B