Technical question pertaining to multiplayer server default commands

[TropicalV2]

How can you block OPs from utilizing certain default commands such as switching their gamemode to creative mode and resetting the time schedule? I'm running a bukkit server and I'm wondering if maybe there's a plugin or a certain or a permissions setting that can make it happen. Thanks.

[Merv]

If you're using Essentials Groupmanager, you might want to make a rank without the /gm or /gamemode permission, by adding a # next to the - essentials.gamemode or whatever. You can use the Admin rank for this and they won't get OP. You can't block commands from OPs because OPs have the top power over everything.