How the option with Recovery during master database restore helped .

Dear all,

Kindly check the following blog .

http://sqllive.wordpress.com/2012/12/13/restore-master-database-with-replace-recovery/

And help me to find the answer for the following question .

what is the role of "WITH RECOVERY" option during master database restore ? OR How "With Recovery" option helped here ?

Thanks,

SKB.