taglinefilesource code
stretch1884drivers/block/floppy.craw_cmd.track = format_req.track << floppy->stretch;
stretch2256drivers/block/floppy.craw_cmd.track = TRACK << floppy->stretch;
stretch2835drivers/block/floppy.cUDP->tracks>>newparams.stretch)
stretch64include/linux/fd.hstretch;  /* !=0 means double track steps */