``opts`` may be NULL or a BSON document with additional command options:

* ``readConcern``: Construct a :symbol:`mongoc_read_concern_t` and use :symbol:`mongoc_read_concern_append` to add the read concern to ``opts``. See the example code for :symbol:`mongoc_client_read_command_with_opts`. Read concern requires MongoDB 3.2 or later, otherwise an error is returned.
* ``sessionId``: Construct a :symbol:`mongoc_client_session_t` with :symbol:`mongoc_client_start_session` and use :symbol:`mongoc_client_session_append` to add the session to ``opts``. See the example code for :symbol:`mongoc_client_session_t`.
* ``collation``: Configure textual comparisons. See :ref:`Setting Collation Order <setting_collation_order>`, and `the MongoDB Manual entry on Collation <https://docs.mongodb.com/manual/reference/collation/>`_. Collation requires MongoDB 3.2 or later, otherwise an error is returned.
* ``serverId``: To target a specific server, include an int32 "serverId" field. Obtain the id by calling :symbol:`mongoc_client_select_server`, then :symbol:`mongoc_server_description_id` on its return value.

Consult `the MongoDB Manual entry on Database Commands <https://docs.mongodb.com/manual/reference/command/>`_ for each command's arguments.
