ld not be verified * OLM_UNKNOWN_MESSAGE_INDEX if we do not have a session key corresponding to the message's index (ie, it was sent before the session key was shared with us)</p></dd></dl><dl><dt class="spec value" id="val-inbound_group_session_id_length"><a href="#val-inbound_group_session_id_length" class="anchor"></a><code><span class="keyword">val</span> inbound_group_session_id_length : <span><a href="../Types/InboundGroupSession/index.html#type-t">Types.InboundGroupSession.t</a> Ctypes_static.ptr</sp