Accounting rules - symbol/diagram/attribute to use

Hi,

I am modelling L5 business processes and need to add accounting rules - movement of money between accounts, ie,  Debit customer account, credit Receipt account. These rules are different from Business rules and are not needed for a business person to execute the process.

 I looked at different diagrams (Data models, Information models), but none is really providing me with a solution.  

Has anyone captured something like this before? Or, maybe has a suggestion for me?

Thanks

Santa