index header capture

[John Sica]

Doing backups over the internet has forced me to consider eliminating 
the indexes from the backup.
 
Some time ago, I was able to capture only the part of the index I needed 
to re-create the index.  I used a command similar to this.

dd if=index.A of=index.head bs=1 count=160

This command captures the first 160 bytes of the file (index) and 
outputs it to another file called index.head.

However, when this file (index.head) is renamed to index.A, it does not 
give me all the information I need to create the index.  Does anyone 
know the minimum number of bytes needed to create an index.

Thanks,

John