HelenOS sources

IOF_DATA           56 uspace/app/vuhid/hids/bootkbd.c 	INPUT(IOF_DATA | IOF_VARIABLE | IOF_ABSOLUTE),
IOF_DATA           67 uspace/app/vuhid/hids/bootkbd.c 	OUTPUT(IOF_DATA | IOF_VARIABLE | IOF_ABSOLUTE),
IOF_DATA           80 uspace/app/vuhid/hids/bootkbd.c 	INPUT(IOF_DATA | IOF_ARRAY),

HelenOS homepage, sources at GitHub