Group membership is itself expressed by grants whose subject is the group, so one grant from the owner can reach many people and adding or removing a member is one grant or one revocation. Membership is evaluated late: when a member is removed, every node whose readers included the group loses that member at once. Nested groups are allowed in the data model; the first implementation caps evaluation depth and marks deeper nesting an open question.

No group concept. The roadmap asks for "one capability granting several keys at once" and a permanode per space; this audience with the Group permanode is that.