Derivation Rules in FICO

Hi all,

I am new to FICO and i need to work on the Derivation Rules Txn KEDR in FI/CO.

That is i need to know the

1. Purpose

2. Example

3. Then walk through the process.

Actually i dont know anything about the Derivation Rules as well as KEDR. And i dont know what is the link between the KEDR and Derivation Rules.

Can anyone guide me on this. It will be a great help if anyone help me out in this.

Thanks in advance.......