Moded Minecraft server permissions?

I'm an admin on a modded Minecraft server running the new direwolf 20 pack on Minecraft 1.7.
We're using the permissionsEX plugin.
what I need to know is what permission node do I need to add to allow use of the open blocks mod's inventory restore command.
( the command looks like this:
"ob_inventory restore <playername> <inventory backup filename>". )
Also if there's a permission to add use of specific commands like the one mentioned above, what would be the proper way to set that up?