Optionalanchorthe anchor node's crdt id, if anchored
Optionalanchorthe anchor's horizontal origin, if anchored
Optionalanchorthe anchor threshold, if anchored
Optionalanchorthe anchor type, if anchored
the block's current version (selects the point encoding for lines)
the unread tail of the block, preserved for round-tripping
the layer name
the block's minimum reader version
the node's crdt id
the block-type discriminant
whether the layer is visible
the
0x02tree node block — a group's metadata (layer name/visibility)