How Ruby directives works with Ruby Pack() method?

I went through the Ruby documents,where i got familiared with different directives but not how and when to use them.So may I have small help on the same,just to get start to see how those works in the real life coding?

B and b

m and M

H and h

P and P



Thanks in advance!

Can you please be more clear with your query.....
It will bw helpful for us to resolve your prob....