keymaps[][MATRIX_ROWS][MATRIX_COLS] = {

Is it a printer? And for a simplified example, int p[][3][4] means?

Or a 3D matrix?

answer: this is a 3d matrix, the first division means keyboard layers, auto defined when matrix initialized.

eg int 3dmatix[][3][4]={{{0,1,2,3},{4,5,6,7},{8,9,10,11}},{{20,21,22,23},{24,25,26,27},{28,29,30,31}}}; initialized a 3d matix, the first division is caculated here is 2,so 3d matrix[2][3][4].

and we can define a pointer int *p[3][4]=3dmatrix[0];