It allows groups of accounts to vote on and enact proposals, mainly to allow certain proposal types to be decided on quickly in emergency situations, or to delegate low risk parameter updates to a smaller group of individuals.
Members vote on proposals, with just simple one vote per member, no deposits or slashing. More sophisticated voting could be added.
A permission acts as a filter for incoming gov proposals, rejecting them if they do not pass. A permission can be anything with a method `Allows(p Proposal) bool`. They reject all proposals that they don't explicitly allow.
This allows permissions to be parameterized to allow fine grained control specified at runtime. For example a generic parameter permission type can allow a group to only change a particular param, or only change params within a certain percentage.
