qmk_firmware/keyboards/boardsource/4x12/4x12.h

#pragma once
#include "quantum.h"

#define LAYOUT_ortho_4x12( \
    K00, K01, K02, K03, K04, K05, K06, K07, K08, K09, K10, K11, \
    K12, K13, K14, K15, K16, K17, K18, K19, K20, K21, K22, K23, \
    K24, K25, K26, K27, K28, K29, K30, K31, K32, K33, K34, K35, \
    K36, K37, K38, K39, K40, K41, K42, K43, K44, K45, K46, K47 \
    ) { \
        {K00, K01, K02, K03, K04, K05, K06, K07, K08, K09, K10, K11}, \
        {K12, K13, K14, K15, K16, K17, K18, K19, K20, K21, K22, K23}, \
        {K24, K25, K26, K27, K28, K29, K30, K31, K32, K33, K34, K35}, \
        {K36, K37, K38, K39, K40, K41, K42, K43, K44, K45, K46, K47} \
    }