Offset, Hex	Size		Description

0		Word		5AA5h signature

2		32 bytes	1st line of description entered when image created.

22		32 bytes	2nd line of description entered when image created.

42		190 bytes	Unknown data. Looks like ascii formatted with attribute bytes? not needed for disk copy.

100		byte		Disktype.
				04h=Apple
				05h=FM
				07h=MFM
				08h=Amiga
				Other values unknown so far.

101		byte		StartingCylinder

102		byte		EndingCylinder

103		byte		NumberOfSides

104		byte		TrackIncrement

105		256 words	TrackPosTbl 1 word per track, up to 256 tracks. Sets position of track relative to index.
				Normally a small number to position track start at end of index pulse, track splice may
				be located elsewhere for unusual tracks.

305		256 words	TrackOffsTbl 1 word per track up to 256 tracks. Offsets to raw track data. 
                                Shift left 4 bits to get file offset. Last track before 64K boundary zero
				padded so that next track starts on 64K boundary for DMA purposes.

505		256 words	TrackLngthTbl. 1 word per track, up to 256 tracks. Length in bytes?
705		512 bytes	TrackTypeTable. 2 bytes per track, up to 256 tracks. First byte track options:
				Bit 0 1=Keep track length.
				Bit 1 1=Copy across index.
				Bit 2 1=Copy weak bits.
				Bit 3 1=Verify write.
				Bits 4-7 Unknown options automatically set on unusual tracks. All 0 for normal tracks.
				Second byte same format as DiskType. (see above)

905		8192 bytes.	Unknown data. 32 bytes per track, up to 256 tracks. Usually 20 bytes per track
				actually used. Zeroing this data seems to have no effect on disk write.

2905		5882 bytes	Track fragment. There is always a partial image of track 27 here. Unknown why.
				It does not seem to be used in any way.

4000		to end of file.	Track data begins.