The RSoP (Resultant Set of Policy) is very useful when you need to understand which particular GPO will be applied to the computer. You can use the standard Windows snap-in to view the DeviceLock policy currently being applied, as well as to predict the policy to be applied to a computer.
This article contains instructions on generating the RSoP report.
How-to
To generate RSoP report, start MMC and add the Resultant Set of Policy snap-in manually:
1. Run 'mmc' from the command line or use the Run menu to execute this command;