Program SAPMSM20 Which tables are used to supply the data

Hi,

I am trying to extract the underlying data which is used by the SAPMSM20 program to provide audit information. (Transaction SM20). Does anyone know which tables are used to log the audit information.

Also looking at the output of SM20 the data includes the user entering a specific transaction but not what they do within the transaction i.e. post an invoice, is this logged anywhere else where I can get at it.

Thanks for your help.

Mark.