I wanted to try the DMK container with OpenMSX, and I discovered I'm not able to get a "valid" MSXDOS disk image at all.
I think I never tried this feature before, because any FAT FD disk image editor worked well enough.
By the way the files I create have the FAT located in a strange position and I cant get the directory from within BlueMSX or OpenMSX.
The disk image file looks ok if I open it with ImageDisk, now I'm wondering whether it is something I broke when I extended cpm2.c and cpmdisk.c (which shouldn't be, because I tried reverting the code back to a couple of years ago) or it is just the MSXDOS version I'm using.
TBH there is only one disk image I'm able to boot on the emulators, it is MSXDOS v1 on a 720 raw image.