Version mkgmap-r4586 was committed by gerd on Mon, 05 Oct 2020 support HGT files with 2 * 1801 * 3601 = 12.970.802 bytes 1801x3601-hgt.patch published in April 2020, got lost somehow http://www.mkgmap.org.uk/websvn/revision.php?repname=mkgmap&rev=4586