I'm getting the hang of keyword research using LTP, but I want to know what the result "-no PR" means? There's a result for "0" page rank, and then there's one that says "-no PR". Does that mean it has no page rank? Is there a different between PR 0 and No PR? I found a keyword with a bunch of No PRs, but I want to know what it means for sure before I move on and buy the domain. Thanks.