After the apocalypse, when the nanite swarm blankets the world, only a few of the gestures capable of activating its various functions survive, passed down as jealously guarded secrets in mystery cults and esoteric orders. They are not dissimilar to mudras as Mage: the Awakening used the word.
Depending on the mudras one knows, experimentation could be the equivalent of issuing all sorts of system-rending commands, without necessarily knowing if the manipulator has authorized themselves as a super-user yet. The nanite equivalent of rm -rf could be utterly catastrophic, depending on what it considers files and directories.
Held Action 