The trackpoint of the ThinkPad X1 Tablet Gen 3 detachable keyboard (USB 17EF:60B5) lives in the same HID interface as the touchpad, which is bound to hid-multitouch. The kernel never sets INPUT_PROP_POINTING_STICK for it, so input_id classifies the trackpoint as a plain mouse. Mark it as a pointing stick so libinput applies trackpoint acceleration instead of the mouse acceleration profile. The interface also exposes a second mouse node without a middle button; the modal match keys on the button set (k110,111,112) to select only the trackpoint node and leave the touchpad and the other mouse node untouched.
Files in this directory specify a description of hardware devices, in the form of mappings from modalias-like keys (which identify specific hardware devices) to udev properties. Files in this directory are not read by udev directly. Instead, man:systemd-hwdb(8) compiles them into a binary database. See man:hwdb(7) for an overview of the configuration file format, and man:systemd-udevd.service(8) for a description of the udev daemon. Use 'systemd-analyze cat-config udev/hwdb.d' to display the effective config.