I probably should have mentioned that since track 0 on a bootable disk
is single density (FM) with 26 sectors of 128 bytes, the usable
content of a bootable single-sided TRSDOS-II floppy starts on track 1
with block 32, so the blocks are numbered as if track 0 was the same
format as tracks 1 and up.
I haven't got an image of a double-sided TRSDOS-II floppy, so I don't
know exactly how they map the blocks with that.