Different Bitstream from one flux

[dk1spb]

I have flux file (old version) 123o.flux (http://oldpc.su/0/123o.zip)

fe-inspect.exe -s123.flux:s=0:t=0 -B
and I got:

Aligned bitstream from 0.000ms follows:
000000 0.000 : X-X-X-XXX-X-XX-XXX-X-XX-XXX-X-XX-XXX-X-XX-XXX-X-XX
....

after updrade-flux-file to new version:
fluxengine.exe inspect -s123.flux -c0 -h0 -B
and I got:

Aligned bitstream from 0.000ms follows:
000000 0.000 : X-XX-XXX-XX-XXXX-XX-XXXX-XX-XXXX-XX-XXXX-XX-XXXX-X

Why bitstream so different?
Also please, could you describe that mean x-xx-xxx?
For example: 0x90 is a bitstream 10010000, MFM bitstream is 1001001001010100