workflow report - how to query Action and Resolution changes

Hi

I am trying to prepare a workflow report, showing Action, Resolution and State changes of a workitem by time. The report should show the flow of workitem through various Actions and Resolutions against timestamp.

Using BIRT I am not able to find where Action and Resolution changes are stored. I am able to get the values of all other custom attributes as well as state changes by time. But I am specifically interested in knowing the changes to Action and Resolution.

The other option is to extract the Workitem History from the database, but I am not able to find this anywhere in the tables.

Can anyone help me to locate the Action, Resolution and Work Item history in the tables, which can be queried through BIRT?

Thanks in advance.

Bala