what open source software use qrtr?

i do now sure if can put this question here.
i see libqmi supprort qrtr, but i do not know what open source sofware use it, and how to use?

another question is .
as i know, one Quallcomm device can support qtrt and qmi at the same time.
one usb interface for qrtr, and another usb interface for qmi_wwan, the others usb interface for dm/at/modem ports.
although can send qmi over qrtr, but in fact qrtr is remote-IPC mechanism.
so i think maybe qrtr like dm/at/modem ports, do not belong to libqmi?

or maybe my understanrd to qrtr is wrong?