19. The computing device of claim 17 , wherein the specified metadata source comprises a folder; and wherein further the each entry in the specified metadata source comprises an executable file in the folder.
20. The computing device of claim 19 , wherein the processing unit performs further steps comprising: determining, for each executable file in the folder, whether the each executable file is signed, if the user-specified preferred types of software restriction policy rules comprise a specification of a publisher-based rule.