The interesting parts: Capabilities describe both uniqueness and read-write ability. `iso` is fully unique and hence sendable, `trn` and `val` are write-unique

The interesting parts: Capabilities describe both uniqueness and read-write ability. `iso` is fully unique and hence sendable, `trn` and `val` are write-unique (but `val` is also sendable since it isn't writable). The `tag` capability allows identity/message sending and is fully sendable Recover blocks and automatic receiver recovery allow creation/usage of isolated data if only sendables are used from the external environment. Only sendables can be included in messages. Actors have `ref` access to themselves but `tag` access to other actors.