qmk-dactyl-manuform-a/layouts/default/ortho_2x3/default_ortho_2x3/keymap.c

#include QMK_KEYBOARD_H

const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
    /*
     * ┌───┬───┬───┐
     * │ A │ B │ C │
     * ├───┼───┼───┤
     * │ D │ E │ F │
     * └───┴───┴───┘
     */
    [0] = LAYOUT_ortho_2x3(
        KC_A,    KC_B,    KC_C,
        KC_D,    KC_E,    KC_F
    )
};