The requiredPermissionMask setting is one of the settings of an Action plug-in that can be configured in its configuration file. For more information, see Assets Server Action plug-ins - configuration settings.
Permission mask validation to check if the current selection of assets and/or folders is valid. The plug-in buttons and menu items are enabled or disabled based on the result of the expression. The result of the validation is combined with the result of the enabledExpression check.
For example, when a plug-in can change metadata, you can check if the user has permission to edit metadata on the selected assets.
A plug-in that needs access to thumbnails an previews
VIEW and VIEW_PREVIEW permissions are required.
A plug-in that needs to change asset metadata
EDIT_METADATA permission is required.
A plug-in that needs access to the orignal file
USE_ORIGINAL permission is required.