can you default the G/L account in Purchase order?

If a material has no material code in SAP, can you default the G/L account in Purchase order or it has to be manually entered?.
If a material has no material code in SAP, we can still, default the G/L account with the help of material groups. We can assign the valuation class to a material group and then in FI-automatic posting, we can assign the relevant G/L account in the Transaction event key. The assignment of a valuation class to a material group enables the system to determine different G/L accounts for the individual material groups.

Is it possible to default certain values for particular fields?

Yes it is possible to default values for certain fields where a parameter id is present.
Step 1 Go to the input field to which you want to make defaults.

Step 2 Press F1, then click technical info push button. This would open a window that displays the  corresponding parameter id (if one has been allocated to the field) in the field data section.

Step 3 Enter this parameter id using the following path on SAP Easy access screen System à User profile à Own data.

Step 4 Click on parameter tab. Enter the parameter id code and enter the value you want as default. Save the usersettings.

Which is the default exchange rate type which is picked up for all SAP transactions?

The default exchange rate type picked up for all SAP transactions is M (average rate)

What are the problems faced when a Business area is configured?

The problem of splitting of account balance is more pertinent in case of tax accounts.

What are the different scenarios under which a Business Area or a Profit Center may be defined?

This question is usually very disputable. But both Business Areas and Profit centers are created for internal reporting. Each has its own pros and cons but many companies nowadays go for Profit center as there is a feeling that business area enhancements would not be supported by SAP in future versions.

There are typical month end procedures which need to be executed for both of them and many times reconciliation might become a big issue. A typical challenge in both of them is in cases where you do not know the Business Area or Profit Center of the transaction at the time of posting.

Is Business area at company code Level?

No. Business area is at client level. What this means is that other company codes can also post to the same business area.

Is it possible to maintain plant wise different GL codes?

Yes. To be able to do so the valuation group code should be activated. The valuation grouping code is  maintained per plant and is configured in  the MM module. Account codes should be maintained per valuation grouping code after doing this configuration.

How do you configure a special GL indicator for Customer?

You can use an existing special GL indicator ID or create a new one. After creating a special GL indicator id, update the chart of accounts and the Reconciliation account. Also as a last step you need to update the
special GL code.

The special GL code should also be marked as a Reconciliation account. Switch on the relevant for credit limit and commitment warning indicators in the master record.

What are Validations and Substitutions?

Validations/Substitutions in SAP are defined for each functional area e.g. FI-GL, Assets, Controlling etc at the following levels
1. Document level
2. Line item level
These need to be specifically activated and setting them up are complex and done only when it is really needed. Often help of the technical team is taken to do that.

What is generally configured in the payment term as a default for baseline date?

Generally document date is configured in the payment term as a default for base line date.