I don't know if this question already happened, but...
The white paper say "The ipns (InterPlanetary Name Space)".
This tutorial say "The Inter-Planetary Naming System".
And, this chapter of book is more hesitant and say two possibilities: "the InterPlanetary Naming System (Name Service?)".
We have three possibilities: "Name Space", "Naming System" and "Name Service"
Well... What is extensive name of "IPNS"?
I was going to do a pullrequest on the book, but I was not sure which one was the right choice.