Constant CONN_HANDLE_NONE 

pub const CONN_HANDLE_NONE: ConnHandle = _; // 65_535u16

The placeholder connection handle NimBLE uses for accesses that did not originate from a peer (BLE_HS_CONN_HANDLE_NONE) — e.g. the local read that fetches a characteristic value when a notification is sent without an explicit payload. Attribute permissions are not checked for those.