How to know the openstack client's default microversion?

Without the version option e.g. --os-compute-api-version, the openstack client submits API requests with certain default microversions. The precise microversions vary with the openstack client's version and the specific task. For example, the --debug option reveals that openstack client 7.1.3 uses Nova microversion 2.89 when attaching a volume to an instance. Is there a simpler way than --debug to find out which microversions the client uses? Is there a command, or perhaps a website where this is documented? Thanks for your ideas! Bernd.