preferred_name: Able to independently walk on even/uneven surfaces and climb stairs with or without railings (i.e., needs no human assist or assist device).
preferred_name_lc: able to independently walk on even/uneven surfaces and climb stairs with or without railings (i.e., needs no human assist or assist device).
label: Able to independently walk on even/uneven surfaces and climb stairs with or without railings (i.e., needs no human assist or assist device).
label_lc: able to independently walk on even/uneven surfaces and climb stairs with or without railings (i.e., needs no human assist or assist device).