Disk II 6-2 Encoding Question

["Bryan Parkoff" <nospam@nospam.com>]

Hello,

    I review page C-4 from Beneath Apple ProDOS book.  The Disk Byte is 
total possible 72, but Disk II chooses only possible 66.  Sixth-four Disk 
bytes are used for data and two Disk bytes as AA and D5 are used for Address 
Field and Data Field.  I am curious why six Disk bytes as 95, A5, A9, CA, 
D2, and D4 are not chosen.  Could it be maximum accurate to read and write 
6-2 encoding?  They have a pair of consecutive zero bits and they do not 
have a pair of consecutive one bits.  Disk II prefers to have a pair of 
consecutive zero bits "AND" a pair of consecutive one bits.  Do you have 
explanation?

Bryan Parkoff