Constant mesh_event_id_t_MESH_EVENT_ROOT_FIXED 

pub const mesh_event_id_t_MESH_EVENT_ROOT_FIXED: mesh_event_id_t = 18;

< when devices join a network, if the setting of Fixed Root for one device is different from that of its parent, the device will update the setting the same as its parent’s. Fixed Root Setting of each device is variable as that setting changes of the root.