%hMFD = (
         Name_of_the_file_without_ext => {
                 Fieldname_1(column A) => 'value M or O(column B)',
                 Fieldname_2(column A) => 'value M or O(column B)',
	.
	.
	.
                 Fieldname_x(column A) => 'value M or O(column B)',
                },
         Name_of_the_next_file_without_ext => {
                 Fieldname_1(column A) => 'value M or O(column B)',
                 Fieldname_2(column A) => 'value M or O(column B)',
	.
	.
	.
                 Fieldname_x(column A) => 'value M or O(column B)',
                },
     );